Watershed classification by remote sensing indices： A fuzzy c-means clustering approach

Determining the relatively similar hydrological properties of the watersheds is very crucial in order to readily classify them for management practices such as flood and soil erosion control. This study aimed to identify homogeneous hydrological watersheds using remote sensing data in western Iran. To achieve this goal, remote sensing indices including SAVI, LAI, NDMI, NDVI and snow cover, were extracted from MODIS data over the period 2000 to 2015. Then, a fuzzy method was used to clustering the watersheds based on the extracted indices. A fuzzy c-mean(FCM) algorithm enabled to classify 38 watersheds in three homogeneous groups.The optimal number of clusters was determined through evaluation of partition coefficient, partition entropy function and trial and error. The results indicated three homogeneous regions identified by the fuzzy c-mean clustering and remote sensing product which are consistent with the variations of topography and climate of the study area. Inherently,the grouped watersheds have similar hydrological properties and are likely to need similar management considerations and measures.

Constructing dataset of classified drainage areas based on surface water-supply patterns in High Mountain Asia

The High Mountain Asia(HMA)region,ranging from the Hindu Kush and Tien Shan in thewest totheHimalaya inthe southwith an altitude between 2000 and 8844 m,holds the largest reservoir of glaciers and snow outside Earth Polar Regions.In the last decades,numerous glaciers and lake areas there have undergone tremendous changes with water redistribution.In order to increase understanding of the pattern of distribution of water resources,and their dynamic changes at the basin scale,a watershed classification based on the water replenishment patterns dataset was constructed.The input dataset are from the Randolph Glacier Inventory V.6.0 and the vector data of rivers and streams.Four datasets were thus obtained:Glacier-fed and Runoff-fed Drainage Area(GRDA),Glacier-fed and Runoff-free Drainage Area(GDA),Glacier-free and Runoff-fed Drainage Area(RDA),and the Glacier-free and Runoff-free Drainage Area(NGRDA),and the numbers of these four types of basins are 87,107,32,and 448 separately.The statistical results show GRDA has the largest surface area,accounting for 82.2%of the total basin area in HMA,mainly in the region of the basin with outflow rivers or streams.Dominated by small basins,the GDA area accounts for the smallest area,only 3.86%and the RDA accounts for 5.62%.For NGRDA,most are with small areas,accounting for 8.32%,and mainly distributes in the closed basin of the Qiangtang Plateau.This dataset provides a fundamental classified data source for research on water resources,climate,ecology,and environment in HMA.The published data are available at https://data.4tu.nl/download/uuid:d07d748f-d10b-4308-9626-199ef05cc9af/and http://www.dx.doi.org/10.11922/sciencedb.923.