Semi-Arid Climate - Science topic

Kory Postma thank you very much for your response.

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

Roland Yonaba thank you for this interesting contribution.

Bests,

Mohamed

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.

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.

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:

Slede minimalne stope infiltracije u inčima / sat za svaku od SCS grupa tla:

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 .:

- Vreme u satima za koje treba odvesti oborine sa površina

- Q količina protoka l / sec - ili h

- 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)

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

Thank you so much Bayan Hussien

Thank you for sharing your latest related research, I will read it carefully!@Yijian Zeng

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

I think, the acceptable range of NDVI index classification between -1.0 to 1.0.

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:

https://www.researchgate.net/publication/325091235_Soil_Porosity_and_Water_Infiltration_as_Influenced_by_Tillage_Practices_on_Federal_University_of_Agriculture_Abeokuta_Ogun_State_Nigeria_Soil.

Best regards

Kifilideen

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.

Dear Mr. Mondal,

You may find the answer (with chemical equation and explanation) in the below article.

Regards,

Indrani Mukherjee

Thank you all of you

Please take a look at the enclosed document..

 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.

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

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...

 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).

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

SALTMED Model provides such information.

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).

Please find some useful PDFs on the issue..

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.

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

No, its required percolation ET, Soil moisture, deep drainage, percolation 

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.

Depending on different factor (Target area,soil and crop,water table,cost,time of irrigation,...)

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

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.. 

Thank you very much, Dr. Ali Hussein and Dr.Jo-Anne Joyce. I get the point and match with the pH data.

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.

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.

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

<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..

Please check the PDF attachments.

It needs to be crop- based....as well 

1. Different osmolytes application,

2. Silicon foliar spray

3. Use of specific PGPR  

 Will be useful during drought stress

i agree with Rafael Anleu  

 Please check the attached links. Greetings.

Dear Rebeca,

Thank you very much.  I appreciate your offer.

Gloria

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.

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. 

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

Almost cetainly you would want to look at metals in the soil.  and other anions and cations present.

you can add gypsum to the soil as conditioner and use mole drain in sub soil 

Their feeding on members of the genus seems to be quite well-established in the literature, going back some decades? 

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

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.

Thomas H. Nash publication concerning lichens.

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)

Dear Faraj,

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

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.

  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).

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

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.

 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. 

Karakum desert can be considered as an potential dust source. You should have a special attention to synoptic pattern for emitted dust transmission.

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.  

As such the Basmati rice is susceptible to drought. Please contact heshashidhar@gmail.com for more information regarding the same.

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

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 

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.

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.

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.

Please read the Annual reports of the Central Arid Zone Research Institute (ICAR), India...or else visit the inst web site.

good luck.

regards

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. 

My Dear Mounir Louhaichi; Here are few links attached please go through them. They may help you. regards and Thanks

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  

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

try SWAT. you can import daily precipitation and other weather data. try to get DEM of finer resolution.

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.