Role of Soil Properties and Precipitation Concentration in Enhancing Floods in Northern Ghana

Abstract

Rainfall and soil inherent properties are natural factors that influence  flood occurrence. The study assessed water infiltration rates  and storage capacities of soils in the Northern and Upper East Regions of Ghana and their contribution floods. The objective was to assess the ability of the soil to absorb hydrological shock from floods and explore ecological tools that could be used to manipulate the soils of the regions to play flood reduction and mitigation roles. A field infiltration test was carried out and precipitation concentration index (PCI) was estimated for over a 30 year period.  Soil bulk density was determined and porosity inferred. The PCI indicated that 100% of rainfall in Northern Region for 1977 - 2012 has been uniform in distribution and should not  pose flood threat assuming  rainfall is the only determinant. For the same period in the Upper East Region, 46% – 54 % of the rainfall distribution is indicative that could be succeptible  to  flash flood. Soil infiltration rates ranged between very slow and extremely infiltration classes (0.5 – 7 mm hr^-1) and slow class (7.75 – 8.18 mm hr^-1) for the Northern and  Upper East regions respectively.. Soil bulk density ranged from 1.54 – 3.13 g cm^-3 with porosity from 19 – 41% for Northern Region and 1.81 – 2.17 g cm‑ and 18 – 31 % for the Upper East Region. These accounts for the inability of the soil to carry the hydrological load during floods. Introduction of trees in combination of vetiver grass as an ecological tool could break and open-up the soil profile to allow more water intake and mitigate flood damage.

 

Keywords: Ghana, soil hydrological load, ecological tool, flood mitigation, soil water intake.