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Hello everyone,
I am doing LULC of the arid region, I have acquired landsate 8 image data from USGS website and I have done preprocess in qgis using semi-automatic classification plugin using the standard tutorial and I have converted by DN into reflections value for LULC. however, I facing difficulties in assigning classes for built-up area and bare soil as they have high overlap spectral values.
besides this, I have also used SAVI as well as Modified bare soil index though it's not helping in my problem.
Anyone can tell me what to do in that case.
Thank you.
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Kory Postma thank you very much for your response.
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definition
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Qin Liu came across the same question with few answers on Research Gate and felt like sharing with you and the experts above
Hope so this will be helpfull
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Quantifying groundwater recharge in arid and semi-arid areas is a very challenging task because recharge amounts are small in comparison with the resolution of the investigation methods. Additionally, it depends on soil characteristics, geology, topography, land cover characteristics and land use, besides being affected by the temporal variability of precipitation and other hydrometeorological variables under arid and semi-arid climates. Several watershed models used to quantify recharge generally provide recharge estimates as a residual term in the water-budget. Which means that the estimation accuracy of recharge is controlled by the measurement accuracy of the various other parameters in the water budget. Moreover, according to the literature, daily time steps are desirable for estimation of recharge because recharge generally becomes a larger component of the water budget at smaller time scales.
How could we minimize the uncertainties accompanying the estimation of groundwater recharge under semi-arid conditions using SWAT model at small scale (around 350 km2 area)? Should the SWAT use be coupled with any other techniques or models (like Hydrus-1D) to get best results? Are you aware of any studies that have used SWAT to estimate groundwater recharge, or the impact of climate change and/or anthropogenic activities on groundwater recharge under arid or semi-arid conditions?
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Roland Yonaba thank you for this interesting contribution.
Bests,
Mohamed
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Who can enlighten me on the different trace fossil species in the attached file? The setting: Distal part of the Miocene Huesca fluvial fan (Ebro Basin, Spain). Semi-arid climate. Dominantly floodplain fines with thin-bedded terminal-lobe and crevasse-splay sandstone bodies. Traces are on the grey-colored (reduction) upper surface of the sandstone beds.
Help is appreciated. Thanks in advance,
Rick Donselaar
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Scoyenia gracilis, I would say, showing the characteristic meniscate backfill and longitudinal striation (poorly visible in some burrow portions in Fig. 3). Probably produced by arthropods.
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i want to find  a formula or a correlation between runoff coefficient using slope and land use (vegetation and type of soil)?
 runoff coefficient and the slope and also land use
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Postoji li formula za izračunavanje koeficijenta oticanja pomoću nagiba i namene zemljišta (vegetacija i vrsta tla)?
želim pronaći formulu ili korelaciju između koeficijenta otjecanja pomoću nagiba i namene zemljišta (vegetacija i vrsta tla)? 
koeficijent oticanja i nagib, kao i upotreba zemljišta
Postoji formula za izračunavanje koeficijenta oticanja pomoću nagiba i namene zemljišta (vegetacija i vrsta tla) uz primenu obrazaca za RC i raznih tabela i dijagrama.
Koeficijenti oticanja racionalne metode
Jedan od parametara u jednačini racionalne metode (Q = CiA) je koeficijent oticanja, C.
Ostali parametri su A, područje sliva; i, projektni intenzitet kiše za oluju određenog intervala ponavljanja i trajanja jednakog vremenu koncentracije sliva; i Q, vršna brzina oticanja olujne vode usled oluje intenziteta i, na slivu područja A i sa koeficijentom oticanja C.
Glavni faktori koji utiču na vrednost koeficijenta oticanja racionalne metode za sliv su namena zemljišta, vrsta tla i nagib sliva. Koeficijent oticanja "C" mora imati vrednost između nule i jedan (koeficijent oticanja postoje tabele i kreće se od 0,3 - 0,95 ).
Korišćenje zemljišta: Površine koje su relativno nepropusne poput ulica i parkirališta imaju koeficijent oticanja koji se približava jednom. Površine sa vegetacijom za presretanje površinskog oticanja i one koje omogućuju infiltraciju kiše imaju niže koeficijente oticanja.
Nagib: Pod ostalim jednakim uslovima, sliv sa većim nagibom imaće više olujne vode i time veći koeficijent oticanja od sliva sa manjim nagibom.
Vrsta tla : Tla sa visokim sadržajem gline ne dozvoljavaju veliku infiltraciju i zato imaju relativno visoke koeficijente oticanja, dok tla sa visokim sadržajem peska imaju veću stopu infiltracije i niske koeficijente oticanja. Američka služba za zaštitu tla (SCS) ima četiri identifikacione grupe tla koje pružaju informacije korisne u određivanju koeficijenata oticanja sliva. Četiri grupe tla identificirane su kao A, B, C i D. Klasifikacija datog tla u jednu od ovih SCS grupa može se tzasnivati na opisu karakteristika tla ili na osnovu izmerene minimalne stope infiltracije za tlo.
Opisne karakteristike četiri grupe tla SCS sažete su u sledećoj listi:
  • Grupa A: Duboki pesak; duboki les; agregirana tla
  • Grupa B: plitki les; peščana ilovača
  • Grupa C: Glinovite ilovače; plitka peskovita ilovača; tla sa niskim sadržajem organskih sastojaka; tla obično imaju puno gline
  • Grupa D: Zemljišta koja nabreknu kada su vlažna; teške gline od plastike; određena slana tla.
Slede minimalne stope infiltracije u inčima / sat za svaku od SCS grupa tla:
  • Grupa A ………… ..0.30 - 0.45 in / h
  • Grupa B ………… ..0.15 - 0.30 in / h
  • Grupa C ………… .0.05 - 0.15 in / h
  • Grupa D …………… ..0 - 0.05 in / h
Podelite sliv na različite načine na osnovu korišćenja zemljišta, nagiba i klasifikacije tla i koristim empirijske dostupne podatke o RC i tako izračunati ponderisane prozne metode koja zavisi od površine svakog dela. Jer površinanije ista na celoj površini, kako orografski, tako i geološki. Zato je moj predlog da podelite slivnu površinu i ponderisati krajni rezultat
Zato treba znati sledeće:
- e koeficijet hrapavosti površine koja se odvodi, npr .:
- ϒ za pašnjake 2-5
- ϒ za plivade 6
- ϒ za neravne ispresečane površine 8-15
- s (sigma) koeficijent oticanja postoje tabele i kreće se od 0,3 - 0,95
- Intezitet oborina um / sat maksimalnih oborina
- Vreme u satima za koje treba odvesti oborine sa površina
- J - pad terena% ili promilima
- Q količina protoka l / sec - ili h
- q modul površinskog očenja sa hektar / sat ul / sec
- F površina slivanja, ha
Postoje i druge metode i razni dijagrami i obrasci, ove su najtačnije ali i zahtevaju tačan opis i odabir tačnih koeficijenata.
Srdačan pozdrav i dobru želju da napraviš dobar rad, Mirko!
PS Podaci o podacima dati su u mojoj knjizi "Hidrotehnički radovi", Vojnoizdavački zavod, Beograd 1979, UDK 656: 628.16 (497.1)
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I am using CropWat to work out an irrigation schedule for various crops including cassava.
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Dear Dr. Upenyu,
The following attachments (research papers) may be of some use in understanding yield response of cassava to fertilization and water regimes.
With best regards
Brahmanand
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Hi!, hope you're having a great day, being safe at home.
I'm from La Paz, Baja California Sur, México, and I'm writting my proposal for my thesis project for my Bachelors Degree in Management and water sciences.
Currently I'm interested in researching the economic assesment methods for ecosystem services (ES), specifically those related to catchment and provision of water.
I should mention that the region where I'll be working is a property located in the upper zone of the watershed (, where the main population are smallholders whose actions have cased the deterioration of the soil due to livestock activities; coupled with the arid climate or the region where the average maximum temperature is 36°C and the mean annual precipitation corresponds to 180-200 mm.
I already understand these phases for making the assesment process:
1. Identify the purpose of the assessment.
2. Identify the geographic scope of the proposal.
3. Identify the ecosystem services located in the geographic scope of the program.
4. Identification and characterization of the economic agents that benefit from the ES.
5. Prioritization and characterization of ecosystem goods and services.
6. Identify the different types of value (use / non-use) that are of interest for their economic valuation.
7. Choice and application of the economic valuation method.
I know that these phases that I have identified may seem clear but, but I have not yet been able to determine the indicators with which I am going to study in the field, and how to apply them to the design of my assesment method.
Hope you can help me, and if you have anny recomendations, I'm open to read what you have to teach me.
Thank you so much!
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Thank you so much Bayan Hussien
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I have known some physical-based models and emperical models, i.e., the original Stefan model (mainly used in permafrost regions) and its modified modes. However, I consider there would be some better methods to quantify the dynamics of frost depth in seasonal frozen soil region.
Due to the characteristics of two-way melting of the soil during the thawing period in seasonal frozen soil regions, the prediction of the frost depth during the thawing period becomes more complicated and difficult. Are there any good methods to quantify the dynamics of frost depth during thawing period?
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Thank you for sharing your latest related research, I will read it carefully!@Yijian Zeng
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Do you know the methods to estimate soil evaporation reliably in cold and arid region (especially with shallow groundwater level) other than in-situ experiments during freezing-thawing period? Some researchers used the Penman-Monteith equation to estimate the evapotranspiration during freezing-thawing period. Since there were not any crops in the freezing-thawing period in farmland, things were then concentrated on figuring out how much soil evaporation released. Things would be more complex if there were some land covers (straw, snow, or residues et al) on the farmland. I don't know whether the ET0 calculated by Penman-Monteith equation can represent the soil evaporation scientificly. If not, are there any other recommanded methods ?
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Thank you! Well, based on our observation in Inner Mongolia, soil evaporation can be considered as zero in freezing periods. However, it shouldn't be zero in the thawing periods, the ET0 calculated in thawing periods increases to a relatively high level. There is no crops in the farmland at all at that time. Thus, there is no transpiration in the thawing periods. Thus, the soil evaporation can not be neglect in thawing periods. Bayan Hussien
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Hi every one
I am studying the effect of the spread of the desert on the
occurrence of dust.
I first seek to change the vegetation of the studied area
My study area has a arid and semi arid climate. My question is about NDVI index classification. I want to know what is acceptable range for indigenous plants or desert shrubs?
Thanks for helping someone
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I think, the acceptable range of NDVI index classification between -1.0 to 1.0.
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Please share your ideas/literatures regarding the measurement of infiltration rate under field condition.
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Dear respected M.R. Yadav,
The best practical way of measuring the infiltration rate is by using a double ring infiltrometer. You can also check this link:
Best regards
Kifilideen
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Good afternoon,
My name is José Bandeira.
I am a doctoral student in agricultural engineering at the Federal University of Ceará.
I am currently working with loss by interception. I intend to investigate the characteristics of throughfall, for example: Distribution of droplet size and diameter reaching the soil and its importance in understanding the other hydrological processes.
This work is being carried out in a semi-arid climate region, with caatinga vegetation.
Faced with this situation, I found articles of his authorship and other collaborators. This article is very good and interesting.
I'd like to know a little about the development of your searches:
1 - What model of dysdrometer used in the project;
2 - I would like to know if there are other equipment equivalent to the dysdrometer, which has the same precision;
3 - With regard to price, I requested a budget here from Brazil and the price is in the range of R $ 52,000.00. What you are using in your searches is in this price range.
Follow my email, if you want to reply here: josebbrasil@outlook.com
Grateful for the attention,
Yours sincerely, José.
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Hello,
We recently published a paper, entitled, European In-Situ Snow Measurements: Practices and Purposes. You can find full-paper in my profile. In this paper we tried to list all possible instruments and methods. I hope that may be a reference for your studies.
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Hello, I have checked some papers where it is mentioned that arid/ semi-arid climatic conditions is responsible for high fluoride concentration in groundwater. Can someone please explain me how it happens!
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Dear Mr. Mondal,
You may find the answer (with chemical equation and explanation) in the below article.
Regards,
Indrani Mukherjee
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Dear Colleagues,
Is there a standard irrigation calendar to apply under saline conditions? 
Some researchers apply just for one week, and others for 2 weeks. I want to try the effect of salinity for two weeks but I did not find  a standard calendar to do this experience.
Thank you
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Thank you all of you
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New methods to estimate evaporation for water surface (Dams)
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I studied two climatic condition i.e. arid and semi-arid. In each climatic condition I selected two statues: 1. Sites with conservation measures named mananged 2. Degraded sites.
These sites have similar conditions in terms of physiographic atributes.
I compared alph (within plots) and beta diversity (between plots) of all plant species.
Q1: in both arid and semi-arid regions alpha diversity was higher in mananged sites than unmananged . . Why?
Q2: above result also occured for beta diversity. But there was not significant different between  unmananged sites in different climatic conditions. While in mananged sites beta diversity was significantly higher in semi-arid region than arid region. Simply unmanagement decline the postive effect of better climatic conditions on beta diversity.
I have some reasons for above results but I need more refrences and discussion.
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 I agree with Ayman that there are many reasons why a managed site should do well than open plots. It does largely depend on the way the plots are managed. However if we look at it in the open plot perspective; herbivory and fire can play a major role in shaping up the community composition and structure in arid and semi arid systems, often overpowering the effect of better rainfall conditions. This may not be a problem in the managed plots. I would suggest looking (if there are any records of such available) into fire history and herbivore densities, or conduct simple herbivore exclusion experiments to assess if there is any improvement in species composition.
Regards,
Sneha.
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Hi,
I need data regarding average yearly topsoil loss in India and Pakistan for the period between 2000-2010. I also need data regarding the percentage soil organic matter (not just carbon content) for these two countries.
Thanks
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India losing 5,334 million tonnes of soil annually due to erosion: Gov ( source : hind , November 26, 2010)
India is losing 5,334 million tonnes of soil every year due to soil erosion because of indiscreet and excess use of fertilisers, insecticides and pesticides over the years, Parliament was told today. About one millimetre of top soil is being lost each year with a total loss of 5,334 million tonnes annually due to soil erosion, Minister of State for Agriculture K. V. Thomas said in a written reply in Rajya Sabha.
The rate of loss is 16.4 tonnes per hectare every year, the minister said while quoting from a study conducted by Central Soil Water Conservation Research and Training Institute (CSWCRTI), Dehradun.Experiments conducted by Indian Council of Agricultural Research (ICAR) indicated that non-judicious and imbalanced use of inorganic fertilisers (NPK) over years may result in deterioration of soil fertility/nutrient deficiencies, Mr. Thomas said.
Assessment of permissible soil loss in India employing a quantitative
bio-physical model by  Debashis Mandaland V. N. Sharda
Soil degradation in all its nefarious forms has serious repercussions on crop and biomass productivity.Assessment of soil loss tolerance limits (SLTLs) (permissible
soil loss) serves as a tool to gauge the potential erosion risk in a given area with regard to longterm sustainability. In this communication, SLTLs in different states of India and at the national level have been quantitatively estimated by employing a biophysical model based upon integration of relevant attributes. The analysis has indicated that soil loss tolerance or T-value varies from 2.5 to 12.5 Mg ha–1 yr–1 depending upon soil quality governing soil resistibility to erosion and depth at a particular location. About 57% area in the country has permissible soil loss of
less than 10.0 Mg ha–1 yr–1, which needs to be treated with appropriate conservation measures. Highest priority needs to be accorded to about 7.5% area where the T-value is only 2.5 Mg ha–1 yr–1 due to soil quality constraints. The methodology and framework developed for estimating T-values has the potential to be applied in different regions or countries of the world. The relative efficacy of the present method was tested with productivity index-based approach. Case study evidences in different watersheds revealed that soil productivity can be maintained at sustainable levels by bringing the erosion rate within tolerance limit.PDF enclosed for further reading...
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I want to get detailed information on the pineapple's climate, thermal, and water needs
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 Dear Dr. Daniel,
Page number 52 from the following web link may be of some help to you. (Threshold critical temperature for Pine apple is 35 degree celsius).
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Deep soil drying due to artificial plantations is an important ecological issue in semiarid regions where ground water is generally unavailable. I have daily soil moisture data at deep layers (θd) in a semiarid plantation on the Loess Plateau. And I also have daily precipitation (P), daily transpiration (T) and daily shallow soil moisture (θs) as affecting factors. My purpose is to quantify the contribution of P, T and θs to the changes of θd, but I am not sure which method should be used. Thanks a lot for any help in advance. 
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Dear Xiaodong,
Plot the time series of the soil water storage is a proper start to analyze the impacts of the affecting factors. Seasonally, the deep soil water content may affected by percolation from upper soil layers due to heavy rainfall event, while its depletion is mainly caused by the root uptake of transpiration. It will be good to plot the seasonal changes of both soil water storage and soil water profiles to identify the infiltration and root uptake.
In Loess Plateau, evolution of the dry layer in deep soil due to plant utilization seems very complicated. It is an issue of long-term interactions among precipitation - soil water - plant water use. Observation data over short term, say one or two years, seems not sufficient to reveal the interactions.
If you hope to reconginize how the infiltration and root uptake affect the soil mositure in deep layers, a SPAC model may be a useful tool.
Good luck.
Luo
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Wheat respond to irrigation application even under shallow water table conditions but regular rains at reproductive stage had very little depletion in soil moisture content.
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SALTMED Model provides such information.
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Dear all! The soil variability in Poland is very common. Thus, we can distinguish areas with optimum, insufficient and excessive humidity even on one field. For this reason I am looking for Visual Indices, which would be helpful to detect such areas. Till now, we were working mainly with NDVI and similar VIs. However, the NDVI is more related to biomass, and thus it is useful to distinguish high and low yield areas, but it does not provide information, if the low yields (biomass) result from the shortage, or excess of water? Any ideas? May be MSI (Moisture Stress Index) would be useful?
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Perhaps therma data would be the best - within one field with one crop, excessively wet areas would be cooler. For now, I don't know about the potential sources of such free data (Landsat 8 has resolution of about 100m, although resampled to 30).
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We are trying to depict the total inorganic N fraction NH4and NO-N status in different growth stages of rice in 3 diff. cultivation techniques like direct seeding, SRI and conventional transplanting. We need similar type of earlier research with which we can compare our observations. 
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how important is snow interception by plant for central Himalayas. Any reference articles.
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It is an important component of snow hydrology as it influences accretion and melt process. Most watershed hydrological models can simulate this process at regional scale using land cover and the threshold temperature for snow as precipitation. 
Here are some related papers:
Brown, Brown, M. E., Racoviteanu, A. E., Tarboton, D. G., Gupta, A. S., Nigro, J., Policelli, F., ... & Hummel, P. (2014). An integrated modeling system for estimating glacier and snow melt driven streamflow from remote sensing and earth system data products in the Himalayas. Journal of Hydrology, 519, 1859-1869.
Li, H. O. N. G., Beldring, S., Xu, C. Y., & Jain, S. K. (2014). Modelling runoff and its components in Himalayan basins. 7th Global FRIEND-Water, Montpellier, France.
Verdhen, A., & Prasad, T. (1993). Snowmelt runoff simulation models and their suitability in Himalayan conditions. IAHS Publications-Publications of the International Association of Hydrological Sciences, 218, 239-248.
Nepal, S., Krause, P., Flügel, W. A., Fink, M., & Fischer, C. (2014). Understanding the hydrological system dynamics of a glaciated alpine catchment in the Himalayan region using the J2000 hydrological model. Hydrological Processes, 28(3), 1329-1344.
Hope this helps.
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What are the success factors affecting the performance of rainwater managment, particularly spate irrigation, to minimize the risk of climate variability and recurrent drought in subsistance dryland production systems?
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This not a direct answer to your question but if you've not come across it before this document entitled "Guidelines for spate irrigation" produced by the Food and Agriculture Organization in 2010 may help answer your question.  It is very comprehensive.  You can download it freely from here: http://www.fao.org/docrep/012/i1680e/i1680e.pdf
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If the daily irrigation amount is determined beforehand and the crop fresh weight determined per pot !
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No, its required percolation ET, Soil moisture, deep drainage, percolation 
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Since urban cities house different species and can have different local temperature due to changing climate. I'm interested if it will be considered as a new Biome or just will it just be considered as a habitat?
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Even though urban cities are a man-made environment, they foster their own kind of ecosystem. I see no reason for why this question of city biomes shouldn't be addressed with good sense.
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Depending on soil type, crop available water need and root depth distributions.
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Depending on different factor (Target area,soil and crop,water table,cost,time of irrigation,...)
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Books and articles on increasing the watertable in urban and rural areas?
Calculation of moisture in the saturated and unsaturated soil and excavation and drilling associated with it?
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I have past 30 years observed temperature and precipitation data available. How can the climate change impact be established using observed data ?
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Check this CORDEX East-Asia site for RCM data. They have multiple RCM-GCM_RCP combinations.  https://cordex-ea.climate.go.kr/main/mainPage.do .
It would be helpful if you add further details on the kind of impact you want to assess. But you can use your observed Precipitation and Temperature data to assess the credibility of the RCMs during historical periods and look at future projections from those you feel comfortable with.  You can do whole lot of different analysis like trend, mean change (future vs historical), impact on extremes indices (like the ETCCDI), ....
Good luck
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Conduct good soil test to determine dominant cation, determine water quality before irrigation and best time t.o irrigate
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It needs to be an integrated reclamation strategy , comprising us of soil physical amendments, chemical amendments and biological amendments  , in addition to soil and water conservation engineering , in order to keep secondary salinization at bay.. 
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Dear researcher, professor, practician, Hydrologist
my name is Ali, I am a student of Gifu university. my research is comparison two small catchment with different vegetation types in central Japan. one part of my research is water quality.
I was measure water quality from broadleaf deciduous and evergreen coniferous forest. and one of my parameters in dissolved oxygen (DO). 
based on my data, DO in coniferous evergreen is always lower than in broadleaf deciduous. who knows the reason?
I try to connect with baseflow data because baseflow in coniferous evergreen is lower than broadleaf deciduous. but some literature said groundwater have low DO. 
based on my data, DO in coniferous evergreen is always lower than in broadleaf deciduous. who knows the reason?
Thank you very much for your help
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Thank you very much, Dr. Ali Hussein and Dr.Jo-Anne Joyce. I get the point and match with the pH data.
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To avoid surface soil salt build up through capillary water movement .
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What are the pedological benefits of improving cereal crop yields in semi-aride areas?
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Yes, rice direct seeding is successful if planted on soils with good physio-chemical properties  and enough water holding capacity. But, weeds problem is still an issue in this system.
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Are these exotics are one of  the reasons  for the depletion of ground water table in nilgiris 
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According to my knowledge, any tree species consumes water depending on its vegetative mass and effective or active depth penetration of the root system. Though there is a general belief that Eucalyptus trees consume more water, there are reports contradicting the same, stating that there are more than 20 species of Eucalyptus & not all of them consume same amount of water. The only argument against growing Eucalyptus is that it should not be done in water scarce region, as these trees can be grown in any dry areas or saline pockets or water logged areas. Other reasons against growing Eucalyptus trees are the ecological & soil fertility problems. As far as Kolar region is concerned, the area is water scarce and experiences recurring drought and hence definitely not advisable to grow any water intensive crops/trees.
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I have calculated the crop water requirement of all the crops grown in the micro watershed of the area 2 Hec. The area is situated in rural part of the semi-arid mountainous region.
Can anyone suggest me the way to calculate the water productivity and water use efficiency? What is the significance for calculating these two common terms commonly used?
How can the efficiency be improved in other ways?
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Please study  the following papers which can be obtained from Researchgate.net:
1-Potato cultivar Marfuna yield and water use efficiency responses to early-season water stress.
2- Response of dryland wheat production and precipitation water productivity to planting date.
3-Water use efficiency and yield of garlic responses to the irrigation system, intra-row spacing and nitrogen fertilization.
4-Water use efficiency of winter wheat under deficit irrigation
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Models, criterion, formula, etc
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<yield indexes are suitable for grain and legumes as in Ceccarelli, S. and S. Grando, (1991). Selection environment and environmental sensitivity in barley. Euphytica 57 157-167, and rely on lesser sensitivity and yield of resistant lines. Under stress their yield is superior but in well fed conditions are giving less. For trees resilience or survival indexes are more appropriate but are specific to case..
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Agricultural saline land is big problem in irrigated tract of western Maharashtra. i just want to know existing status and practices to overcome the same problem. 
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I am working on soil fertility evaluation and classification for upland crops using differences systems, which FCC system from Sanchez was used as a based system. Since I need some experiences and applications from other regions or countries which are to apply for the Mekong Delta, Vetnam
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It needs to be crop- based....as well 
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economical bioregulators/compounds
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1. Different osmolytes application,
2. Silicon foliar spray
3. Use of specific PGPR  
 Will be useful during drought stress
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Is to be applied in the pampean region Argentina.
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i agree with Rafael Anleu  
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I have self made equipment for measuring infiltration rat of the land/ soil. But it has some limitations, in case, at the time of over-flooding. In addition, it is difficult to use it when the surface of the land is light-to-hard one.
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I am interested in wetlands and non-tidal ones and how they keep their animal and plant populations, especially those in dry and semiarid regions and also those placed in high elevations. I would like to know about your experience on this subject and have you approached it, if it is possible.
Thanks
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Dear Rebeca,
Thank you very much.  I appreciate your offer.
Gloria
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Even when plants are not growing watering the soil can cool the environment by feeding the microbes. What do you think?
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Watering soil can LOCALY cool the environment but it is because of latent heat used in evaporation and has nothing to do with the microbiology.
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How does the availability of micronutrient is affected by changing climate scenario and what are the possible management practice specially under extreme erratic events of weather.         
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Dr. Hossam Ismael Sir, Thanks for you very appreciative answer  no doubt we can assess the availability trend of water in terms of moisture over a period of time which is occurred due to erratic change in climate.  But may i know how will asses the depletion of nutrient pattern under a changing climatic scenario. 
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I am working on determining water loss due to open canals used by irrigation districts in agricultural regions of the western United States.  Taking flow measurements throughout the canal system to measure water loss has proven difficult as there are many uncontrollable variables.  Instead I was thinking it would be possible to model irrigation losses from an open canal based on a collection of quantifiable variables related to soil type, canal size/wetted perimeter, and canal riparian zone classification.  For example: you have 10 miles of canal, 3 miles are on a clay base and 7 are on silty loam.  2 miles of silty loam canal is has a riparian zone classified as "overgrown", 4 miles are "moderate" and 1 mile is "bare".  All 3 miles of clay canal are "bare."  Estimated water efficiency values for each section are A, B, C, and D.  Variables could be added for temperature, humidity, canal size, etc to determine water loss in that section.  Does something like this exist as I think it would be an extremely valuable tool.  If not, could someone direct me to other literature related to this subject.  Thank you.
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Thank you all for your responses.  The article links are very helpful.
We will likely continue to measure flows in canals but as you alluded to Rafael, the canal systems we are working in are extremely large and complex with thousands of turnouts for private deliveries and we can not control when irrigators turn water on or off.  So some of our flow measurements have actually increased downstream when an irrigator upstream turns water off. Additionally the manpower and time needed to collect all the measurements is very large.
Instead, I was thinking we could take representative measurements in parts of the canal and then model the entire system.  As I've discussed with my colleagues, a model would require empirical data which we are in the process of collecting but we don't possess the technical background to build.
Again, I appreciate your time and thoughts on this question.
Regards,
Preston
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I am interested in the prime influencers of electrical conductivity in soil; so far groundwater salinity, temperature, and moisture content seem to be the key influencing factors. Does anybody have any suggests as to what else may effect electrical conductivity in soil, other than these three?
Thank you.
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Almost cetainly you would want to look at metals in the soil.  and other anions and cations present.
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Sub-soil sodicity, salinity and calcariousness are going to be the biggest threats in semi arid tropics with irrigated agriculture like subsoil acidity and aluminium saturation in hot humid tropics
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you can add gypsum to the soil as conditioner and use mole drain in sub soil 
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Euphorbia taifensis is a new species of Euphorbia   discovered in Saudi Arabia  in 2007, its fruits are eaten by Hamadryas baboon "Papio hamadryas" in case of severe hunger, it seems very unusual that the fruits are eaten by animals because the genus Euphorbia contains very irritant  diterpenens.
Is there in literature some similar cases?
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Their feeding on members of the genus seems to be quite well-established in the literature, going back some decades? 
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In desert areas drought often coincides with elevated temperatures. I have worked on cuticular transpiration of desert plants and most of the plant species possess stomata on both adaxial and abaxial surfaces.
It seems to be contradictory when these plants should reduce the water loss and increasing the stomata density implies in enhancing the probability to lose water to the dry atmosphere. However, it may be a good solution for cooling down the leaf temperature by stomatal transpiration under high temperatures.
Hence, to better understand the ecology of desert plants, I would like to know whether any morpho-ecophysiological trait has been pointed out as efficient to deal with both stressors at the same time.
Thank you in advance!
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You meant perennials, or the most usual way in a desert is an opportunistic avoidance by setting quickly dormant seeds  or deep roots like in ephemerals. for perennials thrichomes waxes and chlorenchima in defoliated shoots reduce surface area and energy balance. CAM adaptation requires moderate night temperatures. Soil permeability and vegetaton patterns like in Ipomea pesditigris under desretification http://www.resnet.wm.edu/~jxshix/math490-2006/research/Klausmeier-1999-science.pdf.Thus several factors may interact but chilling and movable soils impede any vegetation
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I'm very interested in understanding the sate of the art on hydrogeological modelling with special concern to semi-arid environments in order to implement a system within FEFLOW software.
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That may be a bit too specific, but here is a paper I found in my literature database, that may be of interest. It reviews the capabilities of several (software) codes for numerical modeling of groundwater recharge (through the unsaturated zone) in semi-arid settings. You may find useful findings and remarks especially in the discussion. (see the attached RGate page link)
Also, I did a quick web search on google and found this book which may be insightful as well. You may borrow it for free from a library to check if it's effectively useful to you. (see the attached web link)
Cheers.
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I am working with a doctoral student and we need to calculate water loss from lichens on trees in arid and semi-arid regions in Australia. We have theorised that lichens will act like a water reservoir (and therefore be somewhat equivalent to topsoil), they will recharge by stem flow during rainfall events and loose water when the air is dry. Can we ignore ET and just assume Eo? We have sample all over South Australia, but for most locations only basic temp and rainfall data. So we would need a simple equation to calculate either Eo or ET. Any ideas?
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What is the well field tested relationship between catchment vs pond area for semi arid region of India with flat topography?
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I don't know of any good papers on field testing of catchment vs. pond area for semi-arid regions with flat topography, but remember that "flat" is a relative term and gravity pulls water downhill, so the path that the water takes to the pond is still controlled by slight changes in elevation from place to place in the satellite scene.  There will be more underground water along these paths, because they have been "fed" the most water over many years of wet and dry seasons.  So, find a way to use how light reflectance changes from pixel to pixel, and you may be able to find a way to detect subtle changes in topography that will help you find those paths, when the rain increases.  Also, looking at historical data for water-covered areas can help you do that, too.  There will be more underground water where the most water has been present at the surface in the past.    Your Friend, Dr. Robert K. Vincent (Bob)
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 parameters that has role impact on efficiency of WSP system in arid and semi arid regions
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Dear Faraj,
The principal gross misconceptions concerning WSP are: odour, insect (especially mosquito) breeding, high effluent suspended solids, high land take, high water loss due to evaporation, and groundwater contamination.
Odour. Well-designed, well-maintained and not overloaded WSP do not give
rise to odour nuisance. Odour from anaerobic ponds can be prevented at the
design stage . Odour does occur with overloaded WSP, but not to a greater extent than with other forms of treatment. 
Mosquito breeding does not occur in well-maintained ponds. Mosquitoes
need both water and shade for breeding, and shade is only provided in WSP by
emergent vegetation or grass growing down the embankment into the pond.
This does not occur if the WSP are properly maintained .
High effluent suspended solids. The EU Directive on urban wastewater
treatment (Council of the European Communities, 1991a) permits WSP
effluents to contain up to 150 mg suspended solids per litre, since it is recognised
that most (70-90 percent) of the suspended solids are algae and hence
environmentally less damaging .
High land take. WSP do, of course, require more land than other treatment
processes. However, as noted in Box 1, an honest economic or financial
appraisal will indicate that WSP, even with a high land take, are often the
cheapest option. The question generally is: do you pay for a large land area now,
or for a continuously high consumption of electricity in the future? Land
purchased for WSP can often be a real-estate investment. In member States of the European Union farmers are frequently paid not to farm part of their land. This so-called “set aside” land could clearly be leased by sewerage authorities for WSP.
High water loss. In the arid and semi-arid areas of the Region water is a
valuable commodity, and a high evaporative loss from WSP reduces the quantity
of treated wastewater available for crop irrigation (Section 12). However, this
loss is rarely more than 10 percent even in desert areas (see Design Example No.
3 in Annex I). This lost water does, of course, have a value, but the proper
question should be: is its value higher or lower than the energy costs of
alternative electromechanical treatment?
Groundwater contamination is not a problem if the physical design of WSP
has been properly done. The key parameter is the coefficient of soil
permeability as this determines whether or not the ponds need to be lined. If the coefficient of permeability is > 10–9 m/s and the groundwater is used as a source of potable supply, specialist hydrogeological advice should be obtained. A further important perceived disadvantage of WSP is that they are sometimes considered inferior in some way to other treatment technologies –despite their clear advantages of simplicity, low cost and high efficiency. Aerated lagoons used to be frequently promoted as a better alternative to WSP, but their energy costs are high, and it is not uncommon for the aerators to be permanently switched off. The result is that the aerated lagoon then functions as an anaerobic pond. Provided this is recognised and the resulting anaerobic pond is not overloaded and regularly desludged, BOD removal efficiency can be as high as in the aerated lagoon but
without, of course, its high energy costs.
A more recent technology which is being increasingly promoted is the upflow
anaerobic sludge blanket (UASB) reactor (see, for example, van Haandel and
Lettinga, 1994). This should really only be considered as an alternative to
anaerobic ponds as some form of subsequent treatment is required (and WSP are
noted as being especially suitable for this purpose – see van Haandel et al.,
1996). However, while UASB reactors have been found to be appropriate for
the treatment of high strength industrial wastewaters, there is less experience of
their treatment of domestic wastewaters, especially at temperatures below 20oC
(van Haandel et al., 1996). A two-stage UASB system has been recommended
for the treatment of domestic and municipal wastewater below 20oC, but this is
an even more complex technology and further research and development is
needed before it can be considered a viable option (van Haandel et al., 1996).
High-rate algal ponds (HRAP) hold considerable promise for their primary
purpose, which is the production of large quantities of high-quality algal protein,
rather than wastewater treatment per se (Oswald, 1995). However, despite
many years of research, principally in California and Israel, HRAP are not yet at
the stage of large-scale application. Little has changed since their review in the
WHO Waste Stabilization Pond Design Manual for Mediterranean Europe
(Mara and Pearson, 1987).
Similar arguments can be made in the case of the Advanced Integrated Pond
System (AIPS) recently developed in California (Green et al., 1995b). With
AIPS the wastewater enters a 4-5 m deep facultative pond containing a “digester
pit”, which functions much like an anaerobic pond but, in this case, within the
facultative pond, rather than preceding it. The facultative pond effluent is
discharged into a stirred high-rate pond, then into a settling pond to remove most
of the algae produced in the high-rate pond, and thence into maturation ponds
for biological disinfection. Recirculation of some of the high-rate pond contents
back to the surface layers of the facultative pond ensures odourless conditions in
the latter. Operation and maintenance are thus greater than with conventional
WSP, to which AIPS have not been shown to be superior.
The same is largely true of macrophyte ponds both floating and rooted (the
latter sometimes being called gravel bed hydroponic systems – see Williams
et al., 1995) and also of constructed wetlands (which generally comprise a
selection of both types of macrophytes). Reed beds are
about twice as expensive as WSP. Their operation and maintenance
requirements are significantly higher (Mara and Pearson, 1987) and mosquito
(especially Mansonia spp.) breeding is a serious problem if there is a free water surface.
For more on this topic, please use the following link:
Hoping this will be helpful,
Rafik
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I measured total Iron and Aluminum in water extracts of soil samples (1:10) by an IPC-OES. For our soil quality analysis/index method we like to use, these elements turn out to be incorporated for distinguishing differences between land uses.
The soils have a pH of 7-8, a CaCO3 content of ~30-50% and are located in a semi-arid climate, so I wouldn't expect to find any toxic or harmful concentrations.
Now we measured 0.2-1.2 mg/kg (or 10-140 ug/L) of both elements, but it's hard to find any references on what are "good" or "minimum" values as most research focuses on toxicity (so more acidic soils) or on the solid soil solution.
Can anyone comment on these values or recommend literature on this which can help me establish good/bad/minimum boundary values?
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Dear Jeroen,
We published years ago a paper on Al toxicity indices. You can find the link below. It refers mainly to acid soils, but maybe it can be of some usefulness for you.
Thank you very much, Dr Rao, for the link to the excellent publication of Hem and Roberson. I had a print copy of this publication in the past, but I lost it; I was regretful for that for years. I am happy with the pdf.
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I like to grown some jujube seedlings in my private garden ,so i wish any one to assist me in choosing the suitable rootstock for budding cultivars on. 
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  Dr Ali , I got some interesting work by Dr Bal . The promising rootstocks such as  Z. mauritiana and Z. numularia  have been recommended for alkaline soils of arid region . Some other promising rootstocks are also recommended to be tested  such as Z. mauritiana, Z. jujuba, Z. mistol, Z. oenoplia, Z. numularia, Z. zoaziro, Z. xylopyrus, Z. spina-christi, Z. valgaris, Z. rugosa, Z. lotus, Z. sativa, Z. truncata, Z. incurva, Z. glabrata, Z. mucronata, Z. abyssinica, Z. fumiculosa and Z. oxyphylla. Kindly refer to original work ( DOI: 10.1002/9780470013902.90023718).
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The policy planners are emphasizing to increase the water use efficiency. However, I understand a minimum leaching fraction is essential even for canal water irrigation under arid climates. Arid regions are already facing shortage of good quality water, to meet this shortage poor quality irrigation waters are in use everywhere. I fear, unless magnitude of LR is not considered and met, there must be problems of soil salinity followed by sodicity that is even more difficult to reclaim and manage for crop production for food security.
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use modern irrigation system is first step, also, cover soil surface by polyethylene mulch, save about 20 % of water for plants, adding organic compost for soil is the third option because compost has high water holding capacity and then save water
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In tropical soils especially in semiarid region continuous cropping without manure or Fertilizer depleted soil organic carbon by 30-60%.Long-term experiments showed that Fertilizer and manure under Irrigated conditions increased the organic carbon content in soil.Soils have capacity to sequester carbon upto certain level of saturation.Adopting good agricultural practices ,can the soil organic carbon status be raised to saturation level in tropical areas especially in semiarid regions?
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Soils (Entisols, Inceptisols, Alfisols, Vertisols) under various agricultural land uses under both short and long–long term experiments also showed their potentiality to sequester OC under both arable and submerged conditions  and they still show potential to sequester OC even in humid climates .Tropical Indian soils have considerable amount of 2:1 layer silicates and soil modifiers that ensure good substrate quality. This shows their high potential for C sequestration under appropriate cropping and management. It is thus envisaged that the present SOC stock (around 30 Pg in the first 1.5 m) can further be increased by the use of recommended improved seeds, NPK fertilizers, micronutrients, FYM, and the inclusion of legumes in cropping systems.
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Dozens of papers and reports state that planting pits increase infiltration but none of them state by exactly how much or provide and figures whatsoever. Does anyone have any data in this regard?
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 Does anyone have figures for exactly how much zai/tassa/planting pits increase infiltration?
As pointed out the zai tassa or planting pit is way of harvesting and directing water.
In the arid region the retention and use of water can be dependent on the ability to add the stabilized organic material into the zai. On a sandy soil the increasing of the stabilized will depend of using organic clay complexes to amend the zai. 
The use of clay and/or silt to be included with organic waste will develop those complexes when composted. The mature compost is added in the area of the zai.
When amended the traansformation of the stabilized organoclay complex amounts more percolation of harvested water, more retention and use and facilitiates the mineral nutrition of the crop.
The soil of less than 1% soil organic matter can capture and retain less than 30 units for every 100 unites of the dry soil. On 5% soil organic matter the capture and retention is over 200 units of water in the same 100 units dry soil. The increase of conservation and retention is thus from less than 30 to over 200. 
The improved structure imparted from the organic amendment is able to increase not only the retention but also the percolation and feeds the soil microbial activity so important for high quality yield and health. 
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Karakum is a desert in Central Asia. It occupies about 70 percent, or 350,000 km², of the area of Turkmenistan. Khorasan Razavi is located in northeastern Iran and south of Karakum. I`m going to know it`s effect on dusty days in Iran. Last year, Mashhad city was dusty in some days and months. Is it made by Karakum desert ? 
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Karakum desert can be considered as an potential dust source. You should have a special attention to synoptic pattern for emitted dust transmission.
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Can someone kindly provide suggestions or resources that will help me to derive soil salinity from Landsat images in a semi-arid environment. Thank you in advance
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Dear Glory,
There is a very nice book about your question and more on remote sensing and soil salinity:
"Remote sensing of soil salinization, Impact on Land management, Eds. Graciela Metternicht and J.Alfred Zinck. CRC press. taylor and Francis group. Boca rotan 2009."
According to the this book even the hyperspectral sensors were not very sufficient on soil salinity detection by remote sensing however, some of the studies showed that significant relationship with soil surface salinity and SWIR wavebands ranged around 1450nm, 1950nm and 2450nm.  
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Direct seeding of rice
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As such the Basmati rice is susceptible to drought. Please contact heshashidhar@gmail.com for more information regarding the same.
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What forest manager can do to mitigate effects of climate change in semiarid region?
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extreme climate effect and change in semi arid zone has to do with aridity and accentuated drought and desertification. 
So for forest management in arid and semi arid zone has to do with the measures of mitigation to aridity in these areas with respect to forestry and management,
prediction and early warning forecast, irrigation practice, use of improved and resistant species of crop etc, avoidance of intensified overgrazing, burning of bush and illegal deforestation etc. Check files on mitigation of aridity, drought and desertification vis a vis forest management
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Due to the high consumption of water in the potato, ways to increase the  water productivity in order to maximize water use efficiency and increased production in arid and semi-arid regions is?
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Dear Dr. Ali Reza Yazdani
Water productivity in crop production system is the production output (in terms of money) divided by the volume of water used for production of the commodity (in terms of m3). Hence, it is clear that water productivity in potato can be increased, in principle, by the following ways:
1. By increasing numerator i.e., tuber yield having the denominator i.e., volume of water constant.
2.  Having the numerator i.e., tuber yield constant, by decreasing the denominator i.e., volume of water.
3. By increasing proportionately the tuber yield over volume of water.
Now, keeping these principle in our mind, we may increase water productivity of potato by the following ways:
1. Choosing high yielding germplasm or cultivar, 
2. Finding appropriate period for crop growing with greater crop growth rate and greater interception of solar radiation, this is region specific as this crop is thermosensitive, and cold loving.
3. Appropriate soil and crop management like land cultivation for optimum tilth, spacing, crop protection from insects, pests and weeds, appropriate amount and time of application of fertilizers and manures etc.
4. Choosing suitable method of irrigation like furrow irrigation, skip furrow irrigation to reduce volume of water, drip irrigation to reduce volume of water.
5. Soil cover management like mulching to reduce the water loss through evaporation and avoiding weed infestation.
6. Finally harvesting at right time, storing well to reduce post-harvest loss, and marketing with relative higher prices.
In addition, there are several component technologies also for enhancing the water productivity of potato.
Hope this answer will help you.
Best wishes
KG Mandal 
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We are writing up our work on semi-arid rangeland rehabilitation in South Africa where our core argument is about the contribution that rangeland rehab can make towards climate change adaptation  by increasing the availability of natural forage for livestock. But, climate impacts look likely to increase aridity and therefore water stress and to round the argument out, we would like to be able to say something about revegetation contributing to groundwater recharge in the arid zone if possible (groundwater is the main source of freshwater in our region).  All we can find so far is literature on increased soil moisture under shrubs in the arid zone (relative to interpatch) and literature indicating that vegetation actually reduces groundwater recharge through evapotranspiration etc. Any ideas?
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Dear Amanda,
This is an interesting question, though a cursory search on the Internet for "revegetation ground water recharge" yielded 439,000 results, including multiple pointers to literature directly addressing that issue (not necessarily in arid zones).
My top recommendation would be to first contact Dr. François Engelbrecht (CSIR, Pretoria; he's on RG at https://www.researchgate.net/profile/Francois_Engelbrecht) to explore (1) what's the state of the art in climate change predictions (scenarios) for your area of interest in South Africa, (2) to what extent vegetation cover, infiltration into the ground and ground water recharge are included in current (global or regional) climate models. If this is the case, you may at least have an initial objective model linking these processes. It may be far from perfect, or operate on spatial scales that are too coarse for your purpose, but it's a start.
Second, it is true that vegetation generally does tend to transpire, but that statement really needs to be qualified because many plants endemic to arid regions transpire much less than those in other areas (adaptation). So that effect may or may not be the most important factor to consider in the local water balance.
Third, plants also have other relevant impacts on the local environment. For instance, they tend to grow roots that penetrate, sometimes to great depths, into the ground, and those provide natural channels for water to infiltrate to deeper layers. So plants could well promote ground water recharge too, to some extent, at least during the rainy season. They certainly modify the Bowen Ratio, and affect the runoff.
Fourth, by the same token, to the extent plants shed organic materials which accumulate locally, they tend to favor the build up of a biotic environment, which will typically include animal life too (vertebrates and invertebrates). The latter, in turn, will also modify the soil structure and its ability to store water, as well as probably contribute to a higher water infiltration capacity.
In summary, the relation between revegetation and ground water recharge involves many processes. As usual, nothing is simple once you start looking into the details... I hope this may be helpful in at least stimulating further thoughts.
Good luck in your investigations. Michel.
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I want to estimate subsurface inflow (qbf) from the eastern hardrock aquifer into the downstream part of my study area (attached figure). The area has an arid to semi-arid climate. Long-term average annual rainfall ranges from 14 to 178 mm, with an average of 63 mm. The considered water balance equation is as follow:
qbf=P-(qrunoff+qdischarge+E)- ΔV
where P is rainfall, qrunoff is surface runoff, qdischarge is discharge by springs and qanats, E is evaporation from rainfall and ΔV is the change in groundwater storage. P, qrunoff and qdischarge are known and ΔV is assumed to be negligible. I have no idea about how I can estimate evaporation from rainfall in this condition. Any helps/insights would be really appreciated.
Thank you in advance.
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Dear Azizallah
In this case I think you will need to run a daily deterministic / physical model with variables set up to simulate a weathered rock / very thin soil surface of about 2-10cm (or whatever depth you think is the active system with respect to evaporative processes).  The "soil texture" aspect of the model would need to be represented by variables indicating a low total porosity, low field capacity and low wilting point.  The model then works by simulating a thin wetted soil surface (when it rains), in which water is stored and is available for evaporation from the surface over the next few days as the layer dries out.  I presume you have daily rainfall values?  As you have temperature and Etp, you can calculate atmospheric demand for water and your soil model provides the constraints on the evaporative response.  You will then need to create a submodel relating (regressing) the accumulated evaporation for each year (output from the deterministic model) against rainfall for the year (because the primary determinant of evaporation quantity from year to year will be total rainfall quantity, as you note that annual rainfall is highly variable and is also a key variable in your water budget).  Hopefully you have a sequence of +10 years of rainfall records, the resulting outputs will give some relationship that allows an estimate of evaporative response without needing to partition water to infiltration into the fracture zones and fills in the gap in your water budget.
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Regarding adaptions of prehistoric hominins to drinking water resources, what is the maxima in brackish waters modern humans from native and indigene groups living in such environments can deal with? References regarding this question would be appreciated, thank you in advance!
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Hi Johannes,
I guess you found most of these papers already but these is what I found found about the topic with a quick search through google and google scholar:
- Laell et al. 1944, DESERT CLIMATE PHYSIOLOGICAL AND CLINICAL OBSERVATIONS. The Lancet 244, pp. 491-497
- Gleibermann, L. 1973, Blood pressure and dietary salt in human populations. Ecology of Food and Nitrition 2 (2) pp. 143-156
This one seems to compare the effects of salt intake in different human populations but since I can not directly asses it I don't know whether it only takes sodium into account or if chloride is also dealt with.
- Stevenson, Richard J.; Case, Trevor I.; and Oaten, Megan J. 2010, Salt-Induced Thirst Results In Increased Finickiness In Humans. The Psychological Record: 60 (3), Article 1.
This one is about increased finickness in humans under thirst conditions.
I hope one of these proves usefull. I will probably look up more later.
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Does any one have  publication and idea on windbreaks in arid and semiarid area please? the factors that effect windbreak? the design of windbreak? any thing on windbreaks? thank you.
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Please read the Annual reports of the Central Arid Zone Research Institute (ICAR), India...or else visit the inst web site.
good luck.
regards
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Due to maximum use of spring rainfall in arid and semi-arid and increase water productivity, can spring potatoes in cold areas, we planted in the fall?
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I think it's worthy trying with small plots with different varieties. Potatoes require cool nights to tuberize well, but watch for frosts, like indicated by Daniel. Watch also for excessive rains associated with warm temperature spells, which might increase disease epidemics and require undesirable heavy pesticide applications, even in arid and semi-arid regions. 
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In the literature there are conflicting results. I am looking for hard evidence based on data collection and not just empirical data
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Due to low rainfall, people in central Iran have some amazing ways.
These methods have been developed over several thousand years and may have a higher accuracy than the current academic methods.
For example, in some days of September and October, they put cotton on their roofs in order to check weight change due to wetting. They use this method to determine whether the current year is going to be dry or wet.
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In Sri Lanka farmers use many observational predictions to predict drought. Many biological clues have higher probability to be correct. There are many locally published literature unfortunately not widely available online. refer to this link for some clue. http://archives.dailynews.lk/2004/01/30/fea02.html  
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I want to have information about the of species, plantation area, plantation age as well as hydrological effects of these species in the semiarid and area climate zones.
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Dear Seyed
You can find information in the FAO web site or look at this old book (Evans, Tree Planting for Industrial, Social, Environmental, and Agroforestry Purposes) or try others approach like remote sensing to obtain some information. 
have a nice day
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Arid land including mountains and Piedmont. Thus, we couldn't recognize a unique topographic map. Because topography changes especially in Piedmont area. Stream flow pathway change in ever precipitation event.
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try SWAT. you can import daily precipitation and other weather data. try to get DEM of finer resolution.
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In aprticular I am interested in allotmetric equations using vegetation cover, precipitation, etc.
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You can estimate biomass by using dimensional parameters, i.e., canopy cover, length and width of diameters as has been done by Gholami Baghi et al. (2013). You can download the full pdf , Journal of Rangeland Science, 2013, Vol. 3, No. 4 Gholami Baghi et al.
You can use remote sensing techniques to get information on aboveground biomass and make measurements on large scales. For details see Mundava et al (2014). 
Remote sensing techniques have been used by Porter et al. (2014). They have developed regression models for estimating biomass yields using data from satellite and ground based remote sensing platforms in pasturelands of Montana.
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It is known that woody encroachment is occurring in grassland worldwide. I want to know which factors will affect this process, please give me some relating references.
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