تقييم أداء أساليب التقدير البيئي المكاني لسعة الماء المتاح في ترب منطقة الخليج

Abstract EN

Available soil water capacity (AWC) determines both irrigation depth and frequency, therefore, accurate mapping of its spatial distribution is essential for precision agriculture and sustainable management of soil and water resources in irrigated arid lands.

Since direct measurement of AWC is often difficult, expensive and timeconsuming, its mapping is usually based on spatially interpolated values.

Since the quality of maps and digital models obtained by spatial interpolation is partly determined by the method used, the relative experimental performance of several univariate deterministic and geostatistical spatial interpolators were evaluated to delineate the most accurate and least bias interpolator for AWC in Kharj area.

Evaluation of the relative experimental performance of the different interpolators was based on the cross-validation technique and the bias and accuracy were quantified by mean error and root mean squared error statistics, respectively.

Cross-validation results show that: (i) all interpolators except Thiessen polygon performed surface smoothing in the following order from highest to lowest: inverse distance, inverse squared distance, inverse cubed distance, simple kriging, ordinary kriging, universal kriging (UK) with a second order global polynomial detrending model; (ii) the geostatistical interpolators outperformed the deterministic interpolators in terms of bias and accuracy; (iii) kriging procedures have similar accuracy; (iv) UK is the least biased kriging estimator.

Based on the level of surface smoothing, bias, and accuracy, UK provided the best estimates of AWC and, therefore, UK was used to construct high resolution maps and digital models for AWC and its estimation variance in Kharj area.

These maps and digital models should constitute a major building block of the geodatabase required for geographic information system based precision agriculture and sustainable management of soil and water resources in this vital agricultural area.