Browsing by Author "Araya, Tesfay"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Evaluating in Situ Water and Soil Conservation Practices with a Fully Coupled, Surface/Subsurface Process‐Based Hydrological Model in Tigray, Ethiopia
    (Land Degradation & Development, 2016) Opolot, Emmanuel; Araya, Tesfay; Nyssen, Jan; Al-Barri, Bashar; Verbist, Koen; Cornelis, Wim M.
    In situ water and soil conservation (WSC) practices are a promising intervention to improve rainwater management particularly in the semiarid to dry sub-humid tropics. This study applies a fully coupled surface–subsurface process-based model (HydroGeoSphere) to simulate in detail rainwater partitioning as affected by two in situ WSC practices [terwah+ (TER+) and derdero+ (DER+)] currently under study on Vertisols in Tigray, Ethiopia and to evaluate the treatments in terms of rainwater partitioning. In the TER+ practice, contour furrows of 0·2m wide and 0·1m deep are created at 1·5m intervals between permanent broad beds, whereas in DER+, permanent raised beds 0·6m wide with furrows 0·2m wide and 0·1m deep are created, to minimize runoff and water logging. The model accurately reproduced measured surface runoff (e.g. in DER+: Nash–Sutcliffe model efficiency E = 0·6 for calibration and 0·7 for verification) and soil moisture content (DER+: E = 0·6 for calibration and 0·8 for verification). Runoff depth was lowest under DER+ (50 mm) followed by TER+ (67 mm) and significantly higher in conventional tillage (CT) (160 mm). Simulated transpiration, evaporation and drainage out of the root zone were all higher under DER+ and TER+ compared with CT. The effects of DER+ and TER+ practices on rainwater partitioning were more pronounced in wet years than in dry years. The model proved to be a promising and versatile tool to assess the impact of WSC practices on rainwater partitioning at the field scale.
  • Thumbnail Image
    Item
    Fully Coupled Surface–Subsurface Hydrological Modeling to Optimize Ancient Water Harvesting Techniques
    (Handbook ofWater Harvesting and Conservation: Case Studies and Application Examples, 2021) Cornelis, Wim M.; Verbist, Koen; Araya, Tesfay; Opolot, Emmanuel; Wildemeersch, Jasmien C.J.; Al-Barri, Bashar
    Worldwide, but particularly in drylands, water scarcity has become a major limitation to crop production and to delivering ecosystemservices in general. Likewise, in many regions rainfall is becoming more erratic, with later and shorter rainy seasons, more and longer dry spells, and fewer rainy days (Sillmann et al. 2013), even in cases when total rainfall is increasing (Wu et al. 2013; Greve et al. 2014). This might be linked to anthropogenic climate change (Rockström and Falkenmark 2015). It results in a higher frequency of particularly agricultural droughts – shortage of available water for plant growth – which generally occur more often than meteorological droughts, i.e. shortage of precipitation (Wani et al. 2009). In order to improve food and water security, water harvesting in its broadest sense should be an entry-point activity to enhance crop production through sustainable/ ecological intensification. On a larger scale it contributes to regreening of the landscape, through crops, grasses, shrubs, or trees, hence rendering ecosystem services for society (Stroosnijder 2009). In a broad sense,water harvesting refers to retaining rainwater by in situ and ex situ practices (Dile et al. 2013; Cornelis 2014). In situ practices capture and store water where it falls, whereas ex situ practices collect water from a larger area and convey it to fields for immediate use or to storage systems for later use. Various examples are given elsewhere within this book.