Research on Estimation of Wetland Area Based on Spacial Sampling Method-A Case Study of Ningxia Hui Autonomous Region in China

Abstract

Investigation and monitoring of wetland is an important and fundamental work. Wetland area estimation by systematic sampling would have higher precision than that get by traditional random sampling. In this paper, wetland areas of different types in Ningxia were estimated by spacial sampling method, based on remote sensing data from 2015 to 2016. Results showed that: 1) According to the second national wetland resource inventory database, wetland area in Ningxia was 20.72×10⁴ hm², which decreased gradually from north to south, and Wuzhong had relatively largest areas of lakes and marsh wetland. 2) Based with 210 of 4 km×4 km quadrat sampling grids, estimation of wetland area in Ningxia was 21.70×10⁴ hm², with estimation accuracy of 94.53% and sampling accuracy of 99.78%, which was reliability but the sampling accuracy would decline with the proportion decrease of sampling wetland area. 3) Based with 61 of 4 km×4 km quadrat sampling grids, wetland area in Wuzhong was estimated as 52320.67 hm² with estimation accuracy of 98.58%, occurred in a net increase of 731.78 hm² from 2013 to 2016. In conclusion, the spacial sampling method proposed in this research for wetland resource inventory and dynamic monitoring is available and worth of spreading within certain realms, which would improve the protection, management, restoration and sustainable development for wetland resource.