Jawad Al-Bakri

Incorporating Land Use Mapping and Participation in Jordan

Abstract In this study, analysis of land use and suitability maps for 2 contrasting mountainous ecosystems was used to identify areas where a change from existing to potential land use was required. A socioeconomic survey was carried out to select locations for implementing 2 land management packages with the full participation of farmers. The first package included cultivation of wheat landraces in a high-rainfall site (Ajloun), while the second included community-based rangeland rehabilitation and management, including fodder shrub plantations in water harvesting structures in the low-rainfall rangeland areas (Jiza). Results showed that the average grain and straw yield of wheat landraces was significantly higher than that of the improved cultivars, which could lead to high and diverse farm income. In the low-rainfall site, fodder shrubs increased the overall land productivity and aided in improving the cover of native vegetation. After 2 years of protection, dry matter production (620 kg/ha) in the community-protected location was significantly higher than that at an experimental station (465 kg/ha). Findings from both packages indicated the possibility of improving the suitability of both mountainous areas for rainfed cultivation while conserving agrobiodiversity. Development of the arid areas as open ranges could be enhanced by the introduction of suitable cultivation practices (contour furrows in this study), with a view to improving productivity and rehabilitating the native vegetation.

Intercomparison of Evapotranspiration Estimates at the Different Ecological Zones in Jordan

An estimate of evapotranspiration (ET) is needed for many applications in diverse disciplines such as agriculture, hydrology, and meteorology. The objective of this study was to compare two methods for estimating daily actual ET (ETa) from six sites located in four different ecological zones within Jordan. The first method used the analytical land–atmosphere radiometer model (ALARM) and the dimensionless temperature procedure, whereas the second method used ETa calculated from the FAO-56 reference evapotranspiration. ALARM converts general remotely sensed surface temperatures to aerodynamic temperature. Standard meteorological data from weather stations were used with both methods, and the Moderate Resolution Imaging Spectroradiometer (MODIS)–based leaf area index, surface temperature, and albedo were obtained to estimate ETa, using the former method. A validation study was conducted on an alfalfa field in Jordan Valley using ALARM and the American Society of Civil Engineers’ (ASCE) method, which is very similar to FAO-56 except it uses alfalfa as a reference crop. Because this alfalfa field was irrigated and because of warm air advection, ET rates based on measurements of soil moisture change ranged from about 6 to 10 mm day 1 . For this range, the root-mean-square error (RMSE) for ALARM was 0.87 mm day 1 and the coefficient of determination r 2 was 0.36, whereas the RMSE for ASCE was 1.25 mm day 1 and r 2 0.06. There was good agreement between minimum, maximum, and average ETa for the two methods at all sites except for Irbid, for which the minimum and, consequently, the average were different. Much of the site-to-site and temporal variability was found to be statistically significant. Reasons for this variability include soil types, vegetation cover, irrigation, and warm advection.

Modelling desertification risk in the north-west of Jordan using geospatial and remote sensing techniques

Remote sensing, climate, and ground data were used within a geographic information system (GIS) to map desertification risk in the north-west of Jordan. The approach was based on modelling wind and water erosion and incorporating the results with a map representing the severity of drought. Water erosion was modelled by the universal soil loss equation, while wind erosion was modelled by a dust emission model. The extent of drought was mapped using the evapotranspiration water stress index (EWSI) which incorporated actual and potential evapotranspiration. Output maps were assessed within GIS in terms of spatial patterns and the degree of correlation with soil surficial properties. Results showed that both topography and soil explained 75% of the variation in water erosion, while soil explained 25% of the variation in wind erosion, which was mainly controlled by natural factors of topography and wind. Analysis of the EWSI map showed that drought risk was dominating most of the rainfed areas. The combined effects of soil erosion and drought were reflected on the desertification risk map. The adoption of these geospatial and remote sensing techniques is, therefore, recommended to map desertification risk in Jordan and in similar arid environments.

Estimating Actual Evapotranspiration using ALARM and the Dimensionless Temperature

where Rn (W m-2) is the net incoming radiation, G is the heat flux into the ground (W m-2), and H (W m-2) and E (W m-2) are the sensible and latent (evaporative) heat fluxes into the atmosphere. For the energy balance to close, any part of (Rn G) that does not contribute to E must be converted into H. In order for that to happen, the surface has to have the temperature (Ts) that forces the energy balance to close. Estimation of H (or ET as a residual) over vegetated terrain is based on an aerodynamic temperature (Ti), which is the temperature that gives the correct value of H at a specified value (denoted z0h,i) of the scalar roughness length, zoh, based on Monin-Obukhov Similarity (MOS) theory in the surface sublayer (Brutsaert, 1982; Stull, 1988). Specification of the value of z0h to give the correct value of H for use with a radiometric surface temperature Tr is a difficult problem (e.g., Mahrt and Vickers, 2004); Crago and Suleiman (2005) outlined a method (discussed here in section 2.a) to specify z0h,i and to convert Tr to Ti. In the MOS theory, the flux is proportional to the difference between Ti and air temperature (Ta), with the ratio H / (Ti-Ta) depending on variables characterizing the atmospheric turbulence and the land surface. This relationship can be expressed as (e.g., Brutsaert, 1982): ( ) *

Remote sensing indices for monitoring land degradation in a semiarid to arid basin in Jordan

Spectral reflectance for soils and vegetation of the Yarmouk basin were correlated with surficial soil properties and vegetation biomass and cover. The overall aim of the study was to identify bands suitable for assessing soil and vegetation as indices for land degradation and desertification. Results showed that vegetation was well separated from soils in the shortwave infrared wavelength at 1480 nm. For most sites, the differences in the bandwidths (in the range of 8.5 nm to 90 nm) did not improve the differentiation of vegetation types. For all wavelengths, stronger correlation values (maximum R2 = 0.85) were obtained for vegetation cover when compared with biomass (maximum R2 = 0.54). Soil spectral reflectance tended to increase with salinity, with maximum correlations obtained in the blue wavelengths (470±10 nm, 485±90 nm), followed by green and the NIR bands, where R2 values were around 0.60. Comparing results from radiometer measurements with results obtained from ASTER image bands showed that correlations tended to decrease with decreased spatial resolution for the investigated soil properties. For all wavelengths, spectral reflectance of degraded soils was higher than that for natural vegetation and irrigated crops with partial surface cover. Results of the study showed that the use of remote sensing indices related to vegetation cover and soil salinity would be recommended to map the extent of land degradation in the study area and similar environments. However, spectral unmixing should be applied to improve the correlations between satellite remote sensing data and surficial soil properties.

Soil Surface Wetting Pattern under Trickle Source in Arid Lands: Badia Regions

Arid regions are characterized by fragile soils that differ in behavior according to their physical and chemical compositions. In this study, the wetted soil surface area was measured for four different soil types to assess the impact of the individual soil particles (silt, sand and clay separates) on soil surface wetting area, under different application rates using point source trickle irrigation. Three flow rates were tested 4, 8 and 12 liters per hour (Lph) on four different soil types (silt loam, loam, sandy loam58sand and sandy loam77sand). Soil surface wetted area increases as emitter flow rate increases. The results showed that increasing emitter flow rate from 4 to 8 and to 12 Lph, increased soil surface wetted area by about 60 and 160%, respectively. Soil surface wetted areas in loam soil and silt loam soils were 1.5 and 2.8 times that in sandy loam soils, respectively. Soil surface wetted area increases rapidly with time initially, but then increases at a decreasing rate, until the application rate became in equilibrium with soil infiltration rate. The surface wetted area had good correlation with the percentages of silt, sand and clay soil particles, with regression correlation ranging from 0.90 to 0.97. The trends were increased wetting with clay and silt and decreased wetting with sand. The expected losses on the form of evaporation in arid soils suffering from surface crust, therefore, would increase in soils dominated by silt or clay when compared with sand, indicating that cropping pattern in arid environments should be carefully selected in areas with scarce water resources.

A Comparison Study of MODIS and ASCE Alfalfa Evapotranspiration in a Semiarid Climate

Estimation of evapotranspiration (ET) is needed for many applications in diverse disciplines such as agriculture, hydrology and meteorology. The objective of this study was to compare two methods for estimating ET in a semiarid environment. The first method used ALARM and the dimensionless temperature procedure, while the second method used the ASCE reference ET. The use of the ASCE reference ET approach has been recommended worldwide because it provides reasonable results under a wide range of climatic conditions. Standard meteorological data from a weather station were used with both methods, and MODIS-based leaf area index, surface temperature, and albedo were obtained to estimate ET using the former method. The daily estimates of ET were computed for the summer and fall, 2006 for a 1-km pixel that contains 20 ha alfalfa field in Jordan Valley, Jordan. The root mean square difference between the ASCE and ALARM daily ET was 1.3 mm/day. Generally, the ASCE and ALARM daily ET were comparable although ALARM ET was slightly higher than ASCE ET during the summer. The result of this study suggested that remote sensing combined with ALARM and the dimensionless temperature procedure can be useful and reasonably accurate in estimating daily ET for alfalfa. Future studies are recommended to apply the dimensionless temperature approach for other crops in semiarid environment and other climates. In addition, accurate estimates of ET from remotely sensing data of MODIS can be used for water resources management as well as for drought monitoring.