Trenched and diked contours for sustainable agricultural utilization in changing world; soil hydrological, geomorphological, and physical perspectives from over 70 years of implementation in the Northern Negev

Trenched and diked contours (TDC) are used in hilly arid regions worldwide to reduce runoff and soil erosion. The TDC is based on three parts: ‘runoff contributing area’, trench, and adjacent soil dike on the hillslope contours. Surveys over the Northern Negev indicate the hydrological interrelation between the inter-dike surface and the dike. This study hypothesized that all the TDC parts are hydrologically interrelated. The objective is to analyze the soil's physical properties that influence the interrelation from dike construction until maturation and the influences of these interrelations on soil fertility, salinity, and stability. TDC systems, also known as ‘Shikim’, were constructed by the KKL-JNF (Karen Kayemet L'Israel. The Jewish National Foundation) all over the hills of the Northern Negev, the semiarid region of Israel, from the 1950s until present, which gives the ability to analyze the dynamic of water flows inside the TDC s along their existence. The findings indicate three hydrological interrelations, (i) From the ‘runoff contributing area’ into the trench, which differs between the planted and un-planted types; (ii) From the trench into the dike; (iii) and water migration in the ‘dike’ medium. Along the TDC maturation, the intensity of biological influences on these interrelations increases, leading to increased water mobilization to the trench (planting strip) and into the dike medium. The water migration in the ‘dike’ leads to forming of a soil bed adequate for sustainable agricultural utilization in its' downslope face. The finding of this study will maximize the agricultural utilization of the TDCs and their profitability.