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Rehabilitation of degraded rangelands in Jordan: The effects of mechanized micro water harvesting on hill-slope scale soil water and vegetation dynamics

February 2021
Journal of Arid Environments 185

DOI:10.1016/j.jaridenv.2020.104338

Authors:

Stefan Martin Strohmeier

University of Natural Resources and Life Sciences Vienna

Sayo Fukai

Tottori University

Mira Haddad

International Center for Agricultural Research in the Dry Areas (ICARDA)

Mohammad Alnsour

Wadi fo Sustainable Ecosystem Development NGO

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Overexploitation and climate change accelerate the degradation of Jordan's arid rangelands. Uncovered and crusted soils increase runoff and erosion and hinder the emergence of the native vegetation. Micro water harvesting combined with shrub-seedling plantation have been widely applied to reverse land degradation trends. However, consequential soil water and vegetation dynamics have been rarely assessed, which constrains further out-scaling of the rehabilitation practice to complex environments. In Jordan, an experiment was set up to study the linkages between local rainfall characteristics, soil moisture and the development of out-planted shrub-seedlings. Soil moisture was recorded at approximately weekly time-interval during the rainy and dry season 2017/2018 using a manually operated soil water sensor. Transect monitoring was pursued up and down the slope across four micro water harvesting pits and the interspaces. Data confirmed a significant soil moisture increase inside the pits-bridging intra-seasonal dry spells and soil water potentially deep-percolated into the karstic bedrock underneath. The study found that the out-planted shrubs' stem diameter and height predominantly increased during post rainy season, when the interspaces dried up while the pits continued providing moisture. The results are promising and contribute to integrated research towards halting land degradation and sustainable agro-pastoral development.

Time-space plot: 0-20 cm soil depth (top) and 20-40 cm soil depth (bottom). y-axis represents the hillslope location and rainfall, and x-axis represents time. Soil moisture values inside Micro Water Harvesting (MWH) locations and adjacent up and downhill locations represent an average value of two replicate measurements; all other points in the interspaces represent single measurements. Colors indicate in-situ soil moisture conditions related with thresholds of the Soil-Water-Plant relationship (Field Capacity (FC), Permanent Wilting Point (PWP), Atriplex halimus water Stress Level (ASL)).

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Journal of Arid Environments 185 (2021) 104338

Rehabilitation of degraded rangelands in Jordan: The effects of mechanized

micro water harvesting on hill-slope scale soil water and

vegetation dynamics

S. Strohmeier

, S. Fukai

, M. Haddad

, M. AlNsour

, M. Mudabber

, K. Akimoto

S. Yamamoto

, S. Evett

, T. Oweis

International Center for Agricultural Research in the Dry Areas (ICARDA), Beirut, Lebanon

Tottori University, Tottori, Japan

Watershed and Development Initiative (WADI), Amman, Jordan

National Agricultural Research Center (NARC), Amman, Jordan

USDA ARS Soil and Water Management Research Unit, Bushland, TX, USA

ARTICLE INFO

Keywords:

Rangeland rehabilitation

Land degradation

Surface runoff

Soil moisture

Erosion

ABSTRACT

Overexploitation and climate change accelerate the degradation of Jordan’s arid rangelands. Uncovered and

crusted soils increase runoff and erosion and hinder the emergence of the native vegetation. Micro water har-

vesting combined with shrub-seedling plantation have been widely applied to reverse land degradation trends.

However, consequential soil water and vegetation dynamics have been rarely assessed, which constrains further

out-scaling of the rehabilitation practice to complex environments. In Jordan, an experiment was set up to study

the linkages between local rainfall characteristics, soil moisture and the development of out-planted shrub-

seedlings. Soil moisture was recorded at approximately weekly time-interval during the rainy and dry season

2017/2018 using a manually operated soil water sensor. Transect monitoring was pursued up and down the slope

across four micro water harvesting pits and the interspaces. Data conrmed a signicant soil moisture increase

inside the pits - bridging intra-seasonal dry spells and soil water potentially deep-percolated into the karstic

bedrock underneath. The study found that the out-planted shrubs’ stem diameter and height predominantly

increased during post rainy season, when the interspaces dried up while the pits continued providing moisture.

The results are promising and contribute to integrated research towards halting land degradation and sustainable

agro-pastoral development.

1. Introduction

Jordan is located at the transition zone of the eastern Mediterranean

towards the dry rangeland and desert landscape called ‘Badia’, which

occupies a vast expanse in the east and the south of the country. Around

90% of Jordan’s territory is considered Badia (Ababsa, 2013) and re-

ceives less than 200 mm average annual rainfall. However, despite its

marginal conditions the Badia areas are vital to the country, especially

for agro-pastoralism (Al-Tabini et al., 2012). Over the past decades,

unsustainable land management including mechanized

mono-agriculture and overgrazing by small ruminant herds have

severely degraded Jordan’s Badia soils, native biomass and biodiversity

(Abu-Zanat et al., 2004). Political conicts in the region and the

consequential migration including livestock herders, e.g. as a result of

the 1990s Gulf War (Payne, 2016), added further pressure on the natural

resources. Myint and Westerberg (2014) claim that the palatable dry

biomass production of the Jordanian Badia halved from the 1990s to

2010, which progressively altered the livestock feed supply system.

Grazing routines practiced in Jordan’s drylands, nowadays, mainly

serve health and reproduction purposes rather than covering the live-

stock’s feed demand. Wide Badia areas have been transformed into

sparsely vegetated lands with a crusted soil surface (Oweis, 2017). The

declining rainwater retention and inltration characteristics of the soils

eventually speed up surface runoff and erosion (Strohmeier et al., 2017;

* Corresponding author. C/o National Agricultural Research Center (NARC), Jerash Road, Baqa’, Jordan.

E-mail address: s.strohmeier@cgiar.org (S. Strohmeier).

retired.

Contents lists available at ScienceDirect

Journal of Arid Environments

journal homepage: www.elsevier.com/locate/jaridenv

https://doi.org/10.1016/j.jaridenv.2020.104338

Received 14 April 2020; Received in revised form 11 October 2020; Accepted 12 October 2020

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Jordan’s rangelands, the so called Badia, home of the Bedouins, are threatened through a combination of over-exploitation of the ecosystem services and a changing climate towards drier seasons and highly erratic rainfalls. In the recent decades, the once productive grazing lands transformed into sparsely vegetated and crusted desert grounds not capable of retaining the sporadic rainwater within the landscape - and consequential surface runoff inevitably accelerates soil erosion and gullying. To counter-measure the imminent rangeland degradation the International Center for Agricultural Research in the Dry Areas (ICARDA) is investigating mechanized micro Water Harvesting (WH) based restoration technique using the Vallerani plow. This technique intermediately breaks up the crusted surface soil layers and hard pans to approximately 50cm depth. Thus, creating dispersed micro-catchments, well-protected and suitable for the plantation of shrub seedlings, supporting the initial vegetation growth and eventually leading to shrub-island evolvement over the landscape. However, optimum design, particularly the spacing between the WH plow lines, depend on various environmental conditions. In this research, Rangeland Hydrology and Erosion Model (RHEM) was used to assess degraded rangeland hydrological response to transparently suggest on WH layout optimized for the magnitudes and the occurrence probabilities of runoff, soil erosion and sediment accumulation affecting the storage capacity of the micro-catchments. The study combined physical based modeling and ground truthing through different runoff and sediment related experiments. Preliminary results demonstrate good potential of the RHEM-based WH design approach; case study results will be presented for the first time at the conference. Eventually, a fully developed rangeland assessment system will support transparent target area selection and sound WH design interlinked with a risk analysis approach that accounts for the variable environmental patterns of the Badia.

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Nov 2016

Cymie R Payne

The United Nations Compensation Commission (UNCC) proved to be an innovative institution that implemented a law- based approach to the transition from conflict to peace and to the restoration of war-damaged environmental resources. This chapter illustrates how the UNCC adapted the traditional bilateral compensation commission model to address the substantial environmental damage that resulted from the 1990–1991 Gulf War. The goal of the chapter is to provide guidance for similar occurrences in the future. Conflict over shared oil deposits led Iraq and Kuwait into war. The dispute was notable for the extent to which natural resources played a role: in addition to serving as a pretext for war, natural resources had been both the instruments and victims of aggression. Iraq’s invasion of Kuwait violated the general principles of international law (specifically, the prohibition of aggressive war) and the treaty obligations that Iraq assumed when it joined the UN. Under international law, a nation that breaches certain obligations may be obligated to pay financial compensation in reparation for the damage it has caused. Exercising its authority under chapter VII of the UN Charter, the Security Council established a subsidiary body, the UN Compensation Commission (UNCC), to provide financial compensation for losses caused by Iraq’s illegal actions. The commission reviewed over 2.6 million claims from individuals, corporations, international organizations, and governments seeking a total of approximately US$352 billion in compensation; the claimed losses included the cost of extinguishing the oil well fires, and environmental harm. More than US$52 billion has been awarded to successful claimants from more than 100 nations and international organizations. As of April 2014, US$45.5 billion had been paid for distribution to successful claimants, and only one Kuwaiti claim remained with an outstanding balance. In the broader context of international law, compensation serves as a nonpunitive deterrent that provides a remedy to victims. The Security Council’s decision to include compensation for pure environmental losses was a new step in international law. The UNCC demonstrates that states can be held accountable for wartime environmental damage, and reveals the benefits that can be obtained from multi- lateral engagement and long-term commitment to environmental restoration. The chapter is divided into five major sections: (1) a discussion of the conflict that ultimately led to the establishment of the UNCC, with a particular focus on the role of natural resources in Iraq’s decision to invade Kuwait and the resulting environmental damage; (2) a description of the establishment of the UNCC; (3) a consideration of the legal procedures and principles that shaped the work of the UNCC, including the review of environmental claims; (4) an assessment of the UNCC as an instrument of reparations and post-conflict restoration; and (5) a brief conclusion.

Predicting micro-catchment infiltration dynamics

Article

Mar 2020
CATENA

Rainfall and concentrated flow experiments were carried out on seven micro-catchments (MCs) that were designed to limit soil erosion and allow for water-harvesting. Prediction of infiltration rates within MCs is necessary to design effective hillslope-scale restoration projects. Continuous stage measurements and 3-D models of MC geometry were used to calculate infiltration rates from field experiments. Soil samples and Guelph permeameter (GP) measurements were collected to parameterize a predictive infiltration model in Hydrus 2D/3D. The model result of water velocity into the soil profile was averaged by depth intervals and multiplied by the corresponding MC surface area to calculate a volumetric flow rate. Four parameterizations of changes in conductivity with depth were evaluated within the model framework to determine which would best account for spatial heterogeneity. Use of the maximum field-measured conductivity provided the least biased results, with average error between simulated and measured values across all sites of less than 1%. Model results illustrate the limitations associated with particle-size distribution or GP measurements when used to predict infiltration rates in a numerical model. GP measurements with single ponded heights allowed convenient field measurement of conductivity that worked better than predictions from soil texture. The maximum of several GP samples was more representative of MC infiltration than the mean, so a higher percentile value from a distribution of MC measurements may help to account for complex infiltration processes that are not included in numerical models. This modeling approach will allow testing of process-based hypotheses about rangeland infiltration dynamics, and the development of optimal configurations of MCs at sites being considered for rangeland restoration.

Impact of stone bunds on temporal and spatial variability of soil physical properties: A field study from northern Ethiopia

Article

Jan 2018

In the Ethiopian Highlands, stone bunds are a common practice for soil and water conservation, influencing runoff and erosion processes from sloped agricultural areas. The objective of this study was to investigate how stone bunds affect spatio-temporal relationships of these processes to better understand their impacts on soil water development at the smallholder farmer's field level. Study area was the Gumara-Maksegnit Watershed in Northern Ethiopia, where two representative transects were investigated: One transect crossed a 71 m long field intersected by two stone bunds (SB) traced along the contour. The second transect crossed a similar hillslope without conservation structures at a length of 55 m representing baseline (untreated) conditions (NSB). During the rainy season 2012, bulk density, volumetric water content were monitored as well as tension disc infiltrometer experiments were performed to determine the saturated hydraulic conductivity and to derive soil water retention characteristics. Our observations show that SB decreased significantly soil bulk density in center and lower zones of SB transect compared to NSB. No temporal change was observed. Results targeting the surface soil moisture indicate that infiltration was higher with SB and happened earlier in the rainy season in the zones around the SB. Saturated hydraulic conductivity was positively affected by SB and increased significantly. Improved soil hydrology by SB fields may increase crop yields by higher soil water contents but also by extending the growing season after the rainy season. Therefore, stone bunds are a successful measure to establish climate-resilient agriculture in the Ethiopian highlands.

Rehabilitation of degraded rangelands in Jordan: The effects of mechanized micro water harvesting on hill-slope scale soil water and vegetation dynamics

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