Water infiltration in the dongas soils in subhumid zone in West Africa.

Abstract

This paper focuses on soil erosion problems in the W National Park and its Land use areas. Dongas is a gully erosion that occurs in Karimama district and can be classified into three main types according to their size (i) microdongas (0.20m ≤ depth ≤1m), (ii) mesodongas (1m < depth ≤ 3m), (iii) megadongas (depth > 3m). This study accessed the water infiltration rate in different donga types and its variation through different topographic level at dongas upstream, center and downstream. Double ring infiltrometer was used to determine the infiltration rate of water into the soil. The amount of water per surface area and time unit which penetrates the soil are recorded. Water infiltration rate varied in different types of dongas in the W National Park and its land use areas. Infiltration rate is twice higher in W National Park than recorded values in surrounding area with (i) microdongas : W National Park (28.69 cm/h), Surrounding area (10.22 cm/h); (ii) mesodongas : W National Park (17.66 cm/h), Surrounding area (10.23 cm/h); (iii) megadongas : W National Park (28.92 cm/h), Land use areas (17.54 cm/h). Topography significantly affected water infiltration rate in the study area. Thus, water infiltration rates are statistically different at the three topographic level both in W National Park (Lsd = 2.319***) and the surrounding area (ppds= 1.246***) where the highest values were recorded at upstream (respectively 30.77 cm/h in the W National Park and 18.03 cm/h in the surrounding area). The cumulative water infiltration depth is higher in November which is the wettest month compared to April which is the driest month. Further studies on water temporal and seasonal infiltration are useful to adopt best crop and land management practices that can improve water infiltration into soil and store water for plant and reduce water runoff which causes flooding.