Bari 3 consistently experienced the lowest runoff, both in 1992 when the farmer
failed to weed the terrace beneath the maize crop, and in 1993 when the maize crop
was weeded as normal. This plot differed from the others in that the terraces possessed
a sandy, well-draining soil with no riser ditches. The soil texture encouraged
infiltration and the plot configuration, of low-angle terraces without ditches, gave
more potential for on-plot depression storage and a longer residence time as the
water moves across the three terraces monitored (total length of 16.8 m). Variability
in response was also great for individual rainfall events, as well as seasonal loss and
runoff. This is why meaningful comparisons are only possible through the use of
empirically derived relationships between the key variables at each location.
Regression relationships between total rainfall and runoff, using a complete set
of pre-monsoon and monsoon rainfall events, standardized for each site, have enabled
annual mean runoff coefficients to be calculated. Estimated total runoff as a percentage
of total rainfall was 5–10% for Bari 1, 10 and 11, approximately 3% for Bari
3, and 18–26% for Bari 2 (Fig. 8). For comparison, the monsoon runoff coefficients
for good secondary forest cover and highly degraded forest cover were found to be
1% and 33% respectively (Gardner & Gerrard, 2002)
Bari 3 consistently experienced the lowest runoff, both in 1992 when the farmerfailed to weed the terrace beneath the maize crop, and in 1993 when the maize cropwas weeded as normal. This plot differed from the others in that the terraces possesseda sandy, well-draining soil with no riser ditches. The soil texture encouragedinfiltration and the plot configuration, of low-angle terraces without ditches, gavemore potential for on-plot depression storage and a longer residence time as thewater moves across the three terraces monitored (total length of 16.8 m). Variabilityin response was also great for individual rainfall events, as well as seasonal loss andrunoff. This is why meaningful comparisons are only possible through the use ofempirically derived relationships between the key variables at each location.Regression relationships between total rainfall and runoff, using a complete setof pre-monsoon and monsoon rainfall events, standardized for each site, have enabledannual mean runoff coefficients to be calculated. Estimated total runoff as a percentageof total rainfall was 5–10% for Bari 1, 10 and 11, approximately 3% for Bari3, and 18–26% for Bari 2 (Fig. 8). For comparison, the monsoon runoff coefficientsfor good secondary forest cover and highly degraded forest cover were found to be1% and 33% respectively (Gardner & Gerrard, 2002)
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