Feras Ziadat

A Participatory GIS Approach for Assessing Land Suitability for Rainwater Harvesting in an Arid Rangeland Environment

The dry rangelands of West Asia and North Africa are fragile and severely degraded due to low rainfall and mismanagement of natural resources. Rainwater harvesting (RWH) interventions are used to increase soil moisture content, vegetation cover, and productivity. However, adoption of rainwater harvesting by communities is slow. To understand adoption constraints and to develop options for sustainable integration of rainwater harvesting, a benchmark watershed was established in the dry rangelands of Jordan. The objective is to develop a methodology for identifying the suitability for different rainwater harvesting interventions using participatory GIS approach and field survey. The main biophysical parameters used to assess the suitability for rainwater harvesting were slope, soil depth, soil texture, and stoniness. Criteria for each parameter were integrated and a suitability map was produced using raster-based and polygon-based analysis. To integrate biophysical and socio-economic aspects, the land tenure was superimposed with the suitability map. Options for implementing different rainwater harvesting interventions were identified with the participation of the local communities. Field investigations indicated that the applied approach helped to select the most promising fields. Within two years, four types of rainwater harvesting were implemented in the fields of 41 farmers, covering 62.9 hectares, which helped to increase water productivity (kg/m3) four folds and reducing soil erosion five folds compared to fields without rainwater harvesting. The approach showed that participatory GIS approach may be used to integrate socio-economic and biophysical criteria and facilitate the participation of farmers to introduce rainwater harvesting interventions in dry rangeland systems to mitigate land degradation.

Soil Salinity Mapping by Multiscale Remote Sensing in Mesopotamia, Iraq

Soil salinity has become one of the major problems affecting crop production and food security in Mesopotamia, Iraq. There is a pressing need to quantify and map the spatial extent and distribution of salinity in the country in order to provide relevant references for the central and local governments to plan sustainable land use and agricultural development. The aim of this study was to conduct such quantification and mapping in Mesopotamia using an integrated, multiscale modeling approach that relies on remote sensing. A multiyear, multiresolution, and multisensor dataset composed of mainly Landsat ETM+ and MODIS data of the period 2009-2012 was used. Results show that the local-scale salinity models developed from pilot sites with vegetated and nonvegetated areas can reliably predict salinity. Salinity maps produced by these models have a high accuracy of about 82.5-83.3% against the ground measurements. Regional salinity models developed using integrated samples from all pilot sites could predict soil salinity with an accuracy of 80% based on comparison to regional measurements along two transects. It is hence concluded that the multiscale models are reasonably reliable for assessment of soil salinity at local and regional scales. The methodology proposed in this paper can minimize problems induced by crop rotation, fallowing, and soil moisture content, and has clear advantages over other mapping approaches. Further testing is needed while extending the mapping approaches and models to other salinity-affected environments.

Variation of Soil Physical Properties and Moisture Content Along Toposequences in the Arid to Semiarid Area

Accurate prediction and characterization of the spatial distribution and temporal variation of soil water is indispensable to optimize the use and management of land within dry areas, which suffer from limited arable land and water resources. The objective of this research is to examine the effect of hillslope position and characteristics on soil properties and variation of soil moisture in an arid to semiarid region. Five transects representing toposequences in the transitional Arid to Semiarid Mediterranean region of Jordan were selected to study the effect of hillslope position on soil properties and variation of soil moisture. Four sites representing different hillslope positions were chosen within each transect from the summit down to the toeslope. Soil profile, at each position, was described and sampled for laboratory analyses. Moisture content at different depths was monitored during the rainy season. The results indicated a systematic relationship between topographic characteristics (hillslope position, slope steepness, and curvature) and the particle size distribution. Soil erodibility was found to be indirectly related to topographic position as extrapolated from the consistent relationship with clay content. Soil moisture content was related to the topographic position, the variation in clay content, and vegetation condition. The topographic position was found to govern the flow of water from upper to lower positions, resulting in higher moisture availability at lower positions. The variations of other parameters were not only related to the topographic position of particular soil, but also to the characteristics of the soil at the upper positions, and to the sequence in which that soil is positioned in the toposequence. Understanding the distribution of soil properties and their relationship along the soil-landscape continuum, which is unique to this environment, should improve the prediction of soil properties and improve plans to better manage arid land.

A Participatory GIS Approach to Identify Critical Land Degradation Areas and Prioritize Soil Conservation for Mountainous Olive Groves (Case Study)

Climate change scenarios predict an increase in the frequency of heavy rainfall events in some areas. This will increase runoff and soil erosion, and reduce agricultural productivity, particularly on vulnerable mountainous agricultural lands that is already exhibiting high rates of soil erosion. Haphazard implementation of soil and water conservation (SWC) interventions on scattered fields is inefficient in reducing soil erosion. The objective of this study was to identify areas at high risk of erosion to aid the design and implementation of sustainable SWC using GIS analysis and farmers’ participation approach. A 25 m digital elevation model (DEM) was used to derive layers of flow accumulation, slope steepness and land curvature, which were used to derive an erosion-risk (priority) map for the whole watershed. Boundaries of farmers’ fields were mapped and verified by the community and each field was classified into high, moderate or low erosion risk. Fields with low flow accumulation (top of hill) and/or steep slope and/or convex slope were assigned high erosion risk and therefore high implementation priority. The study showed that more than 64% of the fields were classified into high erosion risk areas. Accordingly, a community-watershed plan was established, revised and approved by the community. Incentive loans to implement SWC measures were distributed to 100 farmers based on the priorities of their fields. Judged by local farmers and using 16 randomly selected fields, 90% of the targeted areas were correctly identified using the erosion risk map. After two years, the conservation measures had led to marked improvement of soil conservation. The approach is simple and easy to comprehend by the community and provides scientific basis to prioritize the implementation of SWC and to target the most degraded areas, which amplify the impact of these in reducing the vulnerability to land degradation.