Abstract:
Uva Province is one of the most prominent provinces where a number of CKDu
patients have progressively increased recently. Since the water and the soil quality
are hypothesized as causative factors for CKDu in Sri Lanka, assessing the soil
erosion and possible sediment deposited areas in the study area is crucial for
understanding the relationship between soil quality and the prevalence of CKDu.
Thus, the prime objective of this study is to investigate any statistically significant
correlation between soil erosion and the prevalence of (CKDu) in the study area.
Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) Sediment
Delivery Ratio (SDR) model was applied to estimate and map the mean annual soil
loss rates of each of the 26 Divisional Secretariats Divisions (DSDs) in the study
area using digital elevation model (DEM), rainfall erosivity (R) map, soil erodibility
(K) map, land use land cover (LULC) map, crop management factor (C) data and
support practice factor (P) data. Furthermore, the frequency of CKDu patients in
each of the DSDs was recorded to compute the correlation. The results revealed that
~39% of DSDs fall into extremely high erosion category (> 60 t ha−1 year−1) where
the lowest numbers of CKDu patients were recorded while ~19% of DSDs fall into
the low erosion category (≤ 5 t ha−1 year−1) where the highest numbers of CKDu
patients were recorded. Furthermore, ~15%, ~12%, and ~15% of DSDs fall into
moderate (5 to 12 t ha−1 year−1), high (12 to 25 t ha−1 year−1), and very high (25
to 60 t ha−1 year−1) erosion categories respectively. Moreover, soil erosion was
skewed (skewness = 0.39), which violated the assumption of normality. Thus, the
Spearman rho statistic was calculated, r (24) = -0.83, P ≤0.01. The direction of the
correlation was strongly negative, which means that the areas with low soil erosion
rates in the study area tend to have a higher number of CKDu patients.
