Rainfall erosivity mapping over mainland China based on high-density hourly rainfall records

[摘要] Rainfall erosivity quantifies the effect of rainfall andrunoff on the rate of soil loss. Maps of rainfall erosivity are needed forerosion assessment using the Universal Soil Loss Equation (USLE) and itssuccessors. To improve erosivity maps that are currently available, hourlyand daily rainfall data from 2381 stations for the period 1951–2018 wereused to generate new R -factor and 1-in-10-year event EI 30 maps formainland China (available at https://doi.org/10.12275/bnu.clicia.rainfallerosivity.CN.001 ; Yue et al.,2020b). One-minute rainfall data from 62 stations, of which 18 had a recordlength >  29 years, were used to compute the “true” rainfallerosivity against which the new R -factor and 1-in-10-year EI 30 mapswere assessed to quantify the improvement over the existing maps throughcross-validation. The results showed that (1) existing maps underestimatederosivity for most of the south-eastern part of China and overestimated formost of the western region; (2) the new R -factor map generated in this studyhad a median absolute relative error of 16 % for the western region,compared to 162 % for the existing map, and 18 % for the rest of China.The new 1-in-10-year EI 30 map had a median absolute relative error of14 % for the central and eastern regions of China, compared to 21 % forthe existing map (map accuracy was not evaluated for the western regionwhere the 1 min data were limited); (3) the R -factor map was improved mainlyfor the western region, because of an increase in the number of stationsfrom 87 to 150 and temporal resolution from daily to hourly; (4) the benefitof increased station density for erosivity mapping is limited once thestation density reached about 1 station per 10 000 km 2 .

[学科分类] 眼科学