基于深度学习和遥感影像的黄土丘陵沟壑区浅沟提取及其发育特征

Extraction and Development of Ephemeral Gullies in Hilly and Gully Areas of Loess Plateau Based on Deep Learning and Remote Sensing Image

摘要:

浅沟侵蚀是黄土高原坡耕地的主要侵蚀方式之一，严重破坏了黄土高原的耕地资源。为探究基于遥感影像的黄土高原浅沟快速识别方法，并分析浅沟变化及其时空分布特征，本研究选取陕西省延安市周屯沟流域浅沟为研究对象，利用高空间分辨率遥感影像与深度学习图像语义分割模型，探究了U-Net和SegNet模型在黄土高原丘陵沟壑区浅沟识别性能，阐明了周屯沟流域浅沟时空分布与发育特征。结果表明： SegNet模型在浅沟识别中具有较好的完整性和准确性，其准确率和召回率分别不小于82.59%和91.12%；浅沟主要集中分布于流域地形破碎的南部区域，在河谷平原地区鲜有浅沟分布，浅沟分布具有丛生特点；2009—2021年间共有215条浅沟消失，938条空间位置未发生明显变化浅沟（原位浅沟），新增1374条浅沟；浅沟沟长主要分布在25~40m之间，沟宽在1.00~1.50m之间，浅沟沟长、沟宽、面积、沟密度、割裂度和沟头前进距离多年间平均发育速率分别为1.66m/a、0.04m/a、1.83m2/a、4.94×10-5km/(km2·a)、5.45×10-6a-1和1.66m/a。流域内“治沟造地”工程实施和油气平台开发以及近年来极端降雨事件频发，极大地促进了流域内浅沟的空间分布变化及形态发育。本研究为黄土高原丘陵沟壑区浅沟识别提供了一种有效方法，同时也为黄土高原地区土壤侵蚀和坡沟治理提供了参考。

Abstract:

Ephemeral gully erosion is one of the main erosion modes on sloping farmland, which seriously damages the farmland resources, exacerbates the contradiction between people and food, and seriously hinders the sustainable economic and social development of the Loess Plateau. In order to explore the identification method and analyze the spatial-temporal distribution and development characteristics of ephemeral gullies in the Loess Plateau based on remote sensing images, ephemeral gullies in the Zhoutungou watershed of Yan’an City, Shaanxi Province were selected as the research object, combined high-resolution remote sensing images and deep learning image semantic segmentation model, the application effect of the U-Net and SegNet model in identifying ephemeral gullies and the spatiotemporal distribution were explored and the development characteristics of ephemeral gullies in the Zhoutungou watershed were cleared. The results showed that the SegNet model had excellent integrity and accuracy in ephemeral gully recognition, with model accuracy and recall no less than 82.59% and 91.12%, respectively. The ephemeral gully length and width between predicted and measured values had RMSE values of 6.78m and 0.50m, respectively, indicating that the model had an excellent recognition effect. Ephemeral gullies were mainly distributed in the southern region of the watershed with fragmented terrain, and there were few ephemeral gullies in the valley plain area. The distribution of ephemeral gullies had a clustered characteristic. Totally 215 ephemeral gullies disappeared, 938 ephemeral gullies (in-situ ephemeral gullies) with no significant changes in spatial location, and 1374 new ephemeral gullies were added from 2009 to 2021. Ephemeral gullies were mainly distributed between 25~40m in length and 1.0~1.5m in width. The average annual development rates of ephemeral gullies in length, width, area, density, dissection degree and head advance distance were 1.66m/a, 0.04m/a, 1.83m2/a, 4.94×10-5km/(km2·a), 5.45×10-6a-1 and 1.66m/a, respectively. The implementation of the gully land consolidation project, the development of oil and gas platforms, and the frequent occurrence of extreme rainfall events in recent years had greatly promoted the spatial distribution changes and morphological development of ephemeral gullies in the study area. The research result can provide an efficient and accurate method for identifying ephemeral gullies in hilly and gully areas of the Loess Plateau, and also provide a reference for soil erosion and slope and gully management in the Loess Plateau.