Improving irrigation efficiency in order to balance water supply and demand has become an urgent need for social development in the northwest of China. In this paper, we propose an irrigation water distribution model based on the genetic backtracking search algorithm (GBSA). This algorithm is composed of two main modules, the vector evaluation genetic algorithm (VEGA) and the backtracking search algorithm (BSA). We applied the GBSA model in the Xijun irrigation district of Heihe River Basin. The VEGA module was first used to optimize water distribution in the irrigation district, and ensure a uniform flow rate and a minimum hydraulic loss in the main canal. Moreover, the advantage of BSA module in rapid water distribution was utilized to further improve the overall water distribution velocity of the GBSA model. To evaluate the performance of the GBSA, both the grey relational analysis and the TOPSIS method were used to comprehensively evaluate its various indicators. The results show that the GBSA can meet the water distribution requirements of the whole canal irrigation system, maintaining uniform flow rate, minimizing unused water and water distribution time to optimize irrigation water distribution. At the same time, the GBSA has better performance compared to other existing methods for irrigation water distribution.

The coast around the Abandoned Yellow River Delta underwent significant changes under anthropogenic disturbance. This study aims to reveal the variation of the coastline, tidal flat area, and intertidal zone slope before, during, and after extensive reclamation during the period of 1984–2019 using satellite remote sensing images. In order to eliminate the influence of the varying water level, a new coastline correction algorithm had been proposed under the condition of insufficient accurate slope and water level data. The influence of seawalls on slope estimation were considered in it. The spatiotemporal evolution of coast had been analyzed and confirmed to be reasonable by comparing with the observed data. The results show that the coast can be roughly divided into a north erosion part and a south deposition part. Affected by reclamation, their tidal flat area in 2019 is reduced to only 43 and 27% of original area in 1984, respectively, which results in a continuous decrease in the tidal flat width. The adjustment of the tidal flat profile makes the slopes steeper in the erosion part, while the slopes in the deposition part remain stable. The reclamation has stimulated a cumulative effect as the disappearance of the intertidal zone, which may lead to the destruction of biological habitats.

This study proposes a novel method to detect short-term erosion and deposition within the intertidal zones based solely on waterlines extracted from high-resolution satellite images. The judgement of erosion or deposition is based on the intersection of waterlines, which can reflect topographic changes. The procedures of the method have been demonstrated by its application to the large Radial Sand Ridges in China, where erosion and deposition are drastic due to the strong tidal currents. The intertidal zones were divided into four elevation zones, and the Sentinel-2 satellite images were used to obtain the spatial distribution of erosion and deposition at each sub-zone. The results show that the drastic erosion and deposition detected are greatly linked with tidal creeks. The results had been further used for preliminary risk assessment of wind power structures within the study area. It is found that the southern wind power structures are more possible at risk. The method is an inexpensive way to preliminarily monitor large intertidal zones.