Ja. Butterworth et al., Hydrological processes and water resources management in a dryland environment II: Surface redistribution of rainfall within fields, HYDROL E S, 3(3), 1999, pp. 333-343
Soil water movement was studied within fields on two different soil types,
a red clay soil and a duplex soil of sand over clay, at the Romwe Catchment
in southern Zimbabwe. Each study site comprised two fields and formed a su
rface water sub-catchment (1.0-2.4 ha) from which runoff was gauged. Soil m
oisture was measured in-situ at up to 20 locations within each sub-catchmen
t over an entire cropping season and the following dry season. Maize was cu
ltivated at both sites according to the farmers' normal cropping practice a
nd crop yields were recorded.
Surface redistribution of rainfall through localised runon and runoff was s
hown to be an important process in both subcatchments with rainfall concent
ration factors between 0.2 and 2.7 for major rainfall events. This process
was a key factor controlling deep drainage to groundwater. Results indicate
that surface water redistribution is of particular importance for groundwa
ter recharge in years with low or evenly distributed rainfall, when it woul
d not otherwise have occurred. The soil water conditions created by surface
redistribution of rainfall are also actively exploited by farmers who vary
cropping practices within fields to maximise crop yields and reduce the ri
sks of crop failure.