Reflectance spectra of water in Lake Tai of East China were measured at 28 monitoring stations with an ASD FieldSpec spectroradiometer at an interval of 1.58 nm over five days in each month from June to August of 2004. Water samples collected at these stations were analyzed in the laboratory to determine chlorophyll-a (chl-a) concentration. Twenty-eight spectral reflectance curves were standardized and correlated with chl-a concentration. Examination of these curves reveals a peak reflectance at 719 nm. Chl-a concentration level in the Lake was most closely correlated with the reflectance near 700 nm. If regressed against the reflectance at the wavelength of 667 nm (R 667 ), chl-a concentration was not accurately estimated at R 2 50.494. Accuracy of estimation was improved to R 2 50.817 using the maximum reflectance. A higher accuracy of 0.

With accelerating urbanization, the regional ecological security pattern (ESP) faces unprecedented threats. The situation is particularly serious in the Loess plateau of China (LPC) due to the fragile ecological environment and poor natural conditions. Constructing an ecological network and optimizing the ESP is significant for guiding regional development and maintaining the stability of the ecological process. This study constructed an ecological security network by integrating the minimum cumulative resistance (MCR) model and morphological spatial-pattern-analysis approach in LPC. Additionally, the optimization scheme of the regional ESP has also been proposed. Results show that the ecological source area is about 57,757.8 km2, 9.13% of the total area, and is mainly distributed in the southeast of the study area. The spatial distribution of ecological sources shows specific agglomeration characteristics. The ecological security network constructed contains 24 main ecological corridors, 72 secondary ecological corridors, and 53 ecological nodes. Referring to the identified ecological sources area, corridors, nodes, and other core components, the “two barriers, five corridors, three zones and multipoint” ESP optimization scheme was presented. This research hopes to provide a valuable reference for constructing the ecological security network and optimizing ecological space in ecologically fragile areas of western China.

Gully development is an important topic in the evolution of modern geomorphology. The study of the development process of gullies is key to understanding the genesis, mechanism and spatial differentiation of loess geomorphology. This study explored the mechanism of the development process of gullies whilst taking into account the erosion characteristics of the gully head area, gully slope area and gully bed area. Based on geographic cellular automata (Geo‐CA), the transition rules were interacted with the fundamental hydraulic principles for gully evolution simulation. Different sediment transfer rules apply to the gully slope area and gully bed area. A simulation model of the loess gully evolution was constructed and implemented based on the loess simulation small watershed. The superior performance of the model was demonstrated by the accuracy evaluation of the model structure and the comparative analysis of the modelling results. Moreover, the model was validated by natural watershed data, and the analytical results indicated the feasibility of the model.