Qian Tan

Robust Planning of Environmental Management Systems with Adjustable Conservativeness under Compound Uncertainty

A factor that impedes the practicability of environmental models is a lack of confidence in system performance stability in the face of uncertainty. This paper presents the development and application of a fuzzy radial interval programming (FRIP) approach for identifying waste diversion plans under uncertainty. FRIP allows uncertain parameters in the formats of radial intervals, conventional intervals, and fuzzy sets to be directly communicated into the optimization process. It can be protected against numerous input fluctuations, generating robust solutions that remain optimal in spite of divergent subjective judgments and changing objective conditions. More importantly, such conservativeness in solutions is proactively adjustable by changing protection levels of constraints according to site-specific features and stakeholders’ expectations, avoiding a significant adverse effect on the system optimality. Other capacities of FRIP include a prior quantification of risks associated with solutions, fulfillme...

A simulation–optimization modeling approach for watershed-scale agricultural N2O emission mitigation under multi-level uncertainties

In this research, an integrated simulation–optimization modeling approach (ISOMA) was developed for supporting agricultural N2O emission mitigation at the watershed scale. This approach can successfully combine soil N2O emission simulation and the consequential mitigation management within a general modeling framework. Also, uncertainties associated with the key soil parameter can be effectively reflected and addressed through adoption of Monte Carlo analysis for the simulation results. The Monte Carlo simulated results were then used to generate fuzzy membership functions that can be consequentially used for emission mitigation management, reflecting the combined uncertainties for N2O emission simulation and mitigation management. The developed ISOMA was then applied to a reservoir watershed in Miyun county of Beijing municipality. In the studying watershed, the simulation model was calibrated and verified. Then, N2O emission from multiple agricultural land-use patterns were predicted. The amounts of N2O emission of four land use patterns (i.e., cash tree, orchard, cropland, and natural forest) were (536.9, 590.8, 653.1), (237.7, 254.4, 275.9), (79.5, 100.7, 105.1), (33.0, 47.3, 61.1) kgxa0CO2xa0eqxa0ha−1xa0year−1, respectively. Two scenarios (i.e., G1 and G2) were set up according to development priorities of local economy and society. Meanwhile, multiple credibility levels were considered according to the risk of N2O emission. The land use patterns could be adjusted according to solutions of ISOMA. The developed methods could help regional manager choose various production patterns with cost-effective agriculture N2O emission management schemes in the Miyun reservoir watershed. The manager also can obtain deeply insights into the tradeoffs between agricultural benefits and system reliabilities.

Analysis of the net water loss in the main reach of the Yellow River

In this study, several methods were employed to identify water losses in several reaches of the Yellow River. Then, a method for calculating the net water loss was developed. Also, annual, decadal and seasonal net water losses were analysed for the main reach of the Yellow River. Net evaporation, seepage and transmission per unit length of the river were estimated. The results showed that in the main reaches, not only the net water loss but also the one per km were varying. The water loss was a major reason for rapid reduction of the stream runoff in the river.