|کد مقاله||کد نشریه||سال انتشار||مقاله انگلیسی||ترجمه فارسی||نسخه تمام متن|
|5770929||1629899||2017||10 صفحه PDF||سفارش دهید||دانلود کنید|
- Reducing sampling size raised uncertainty in soil moisture correlation estimation.
- Estimating correlations need more sites than estimating mean soil moisture.
- Reducing sampling size on middle slope had least impact on correlation estimation.
- Sites on middle slope can be reduced in optimal soil moisture sampling design.
In this study, seven random combination sampling strategies were applied to investigate the uncertainties in estimating the hillslope mean soil water content (SWC) and correlation coefficients between the SWC and soil/terrain properties on a teaâ¯+â¯bamboo hillslope. One of the sampling strategies is the global random sampling and the other six are the stratified random sampling on the top, middle, toe, topâ¯+â¯mid, topâ¯+â¯toe and midâ¯+â¯toe slope positions. When each sampling strategy was applied, sample sizes were gradually reduced and each sampling size contained 3000 replicates. Under each sampling size of each sampling strategy, the relative errors (REs) and coefficients of variation (CVs) of the estimated hillslope mean SWC and correlation coefficients between the SWC and soil/terrain properties were calculated to quantify the accuracy and uncertainty. The results showed that the uncertainty of the estimations decreased as the sampling size increasing. However, larger sample sizes were required to reduce the uncertainty in correlation coefficient estimation than in hillslope mean SWC estimation. Under global random sampling, 12 randomly sampled sites on this hillslope were adequate to estimate the hillslope mean SWC with RE and CV â¤10%. However, at least 72 randomly sampled sites were needed to ensure the estimated correlation coefficients with REs and CVs â¤10%. Comparing with all sampling strategies, reducing sampling sites on the middle slope had the least influence on the estimation of hillslope mean SWC and correlation coefficients. Under this strategy, 60 sites (10 on the middle slope and 50 on the top and toe slopes) were enough to ensure the estimated correlation coefficients with REs and CVs â¤10%. This suggested that when designing the SWC sampling, the proportion of sites on the middle slope can be reduced to 16.7% of the total number of sites. Findings of this study will be useful for the optimal SWC sampling design.
Journal: Journal of Hydrology - Volume 555, December 2017, Pages 41-50