Background Evaluation of the connectivity of the water system structure as a drought helps inland river basins in arid regions to achieve the basis of rivers, lakes, water system connectivity within the basin, to a certain extent, reflects the rationality of the regional water environment and water ecology. The scientific and effective evaluation of the hydrological connectivity of watersheds under the water system structure plays a vital role in the integrated management project of water system. The study of water system pattern and connectivity is an important part of comprehensive water system improvement and ecological restoration of rivers and lakes in arid regions.

Methods We took the Keriya River basin as the study area and extracted the watershed water system information based on multi-source DEM elevation data, specifically using ASTER GDEM, SRTM DEM, and ALOS DEM. Utilizing these datasets, we established a water system pattern and connectivity evaluation index system, as well as water system fractal characteristics, based on the network connectivity analysis method and fractal theory in landscape ecology. By applying the landscape ecology network connectivity analysis method and fractal theory, we developed an evaluation index system for the water system pattern and connectivity, including metrics such as water system circularity (β), node connectivity (γ), and network connectivity (C). The differences and reasonableness of the water system pattern and connectivity in the Keriya River Basin were analyzed and evaluated, allowing us to quantify the morphology of the river network within the basin.

Results 1) The optimal catchment area thresholds of the river network extracted using multi-source DEM were 3.125 km² for ALOS DEMz, 11.7 km² for ASTER GDEM, and 52.65 km² for SRTM DEM, while the geometrical structural parameters of the network were in a narrow range, which proved that the river network of the basin had a better self-similarity characteristic. 2) Multi-source DEM calculations of the watershed hydrological sub-dimension values were ALOS DEM (1.127), ASTER GDEM (1.048), and SRTM DEM (1.041), indicating that the Keriya River Basin was in the juvenile stage of erosion, and that the river network was not yet fully developed. 3) The hydrological connectivity index β and γ increased with increasing resolution of the digital elevation model, with an opposite trend in the C index, and it was also found that the hydrological connectivity was optimal under the alluvial plains, while the overall basin hydrological connectivity was relatively poor.

Conclusions Overall, the DEM resolution affects the results of hydrological connectivity, and the watershed hydro-systems are still in the juvenile stage of development, and the results may provide a theoretical basis for rational planning and integrated management of the hydro-systems in the Keriya River Basin.