Statistical Downscaling of Temperature with the Random Forest Model

The issues with downscaling the outputs of a global climate model (GCM) to a regional scale that are appropriate to hydrological impact studies are investigated using the random forest (RF) model, which has been shown to be superior for large dataset analysis and variable importance evaluation. The RF is proposed for downscaling daily mean temperature in the Pearl River basin in southern China. Four downscaling models were developed and validated by using the observed temperature series from 61 national stations and large-scale predictor variables derived from the National Center for Environmental Prediction–National Center for Atmospheric Research reanalysis dataset. The proposed RF downscaling model was compared to multiple linear regression, artificial neural network, and support vector machine models. Principal component analysis (PCA) and partial correlation analysis (PAR) were used in the predictor selection for the other models for a comprehensive study. It was shown that the model efficiency of the RF model was higher than that of the other models according to five selected criteria. By evaluating the predictor importance, the RF could choose the best predictor combination without using PCA and PAR. The results indicate that the RF is a feasible tool for the statistical downscaling of temperature

Trends of major hydroclimatic variables in the Tarim River basin during the past 50 years

The nonparametric Mann-Kendall test was used to detect the trends of major hydroclimatic variables in the Tarim River Basin, the largest inland river basin in China for the period of 1960-2007. Results showed that both mean annual air temperature and precipitation experienced an increasing trend, while annual streamflow demonstrated a mixed trend of decreasing and increasing: The mountainous region upstream showed an increasing trend and the region downstream exhibited a decreasing trend. impacts of the increased air temperature on streamflow have shown different characteristics depending on location and seasons: it has positive effect on the runoff at mountainous region due to snowmelt and glacier-melt in spring, but negative effect on the runoff at plain area due to the increase of actual evaporation in summer. in addition, human activity contributed to the declining of streamflow in the arid plain oases at downstream of the Tarim River Basin. The results obtained in this paper can be used as a reference for the planning and management of water resources to maintain the health of the river system. (C) 2009 Elsevier Ltd. All rights reserved

First-order reliability method for estimating reliability, vulnerability, and resilience

Reliability, vulnerability, and resilience provide measures of the frequency, magnitude, and duration of the failure of water resources systems, respectively. Traditionally, these measures have been estimated using simulation. However, this can be computationally intensive, particularly when complex system-response models are used, when many estimates of the performance measures are required, and when persistence among the data needs to be taken into account. In this paper, an efficient method for estimating reliability, vulnerability, and resilience, which is based on the First-Order Reliability Method (FORM), is developed and demonstrated for the case study of managing water quality in the Willamette River, Oregon. Reliability, vulnerability, and resilience are determined for different dissolved oxygen (DO) standards. DO is simulated using a QUAL2EU water quality response model that has recently been developed for the Oregon Department of Environmental Quality (ODEQ) as part of the Willamette River Basin Water Quality Study (WRBWQS). The results obtained indicate that FORM can be used to efficiently estimate reliability, vulnerability, and resilience.Holger R. Maier, Barbara J. Lence, Bryan A. Tolson, and Ricardo O. Fosch

Adaptation of water resources systems to changing society and environment: a statement by the International Association of Hydrological Sciences

Hydrol. Sci. J.-J. Sci. Hydrol.ISI Document Delivery No.: EB2CDTimes Cited: 0Cited Reference Count: 153Ceola, Serena Montanari, Alberto Krueger, Tobias Dyer, Fiona Kreibich, Heidi Westerberg, Ida Carr, Gemma Cudennec, Christophe Elshorbagy, Amin Savenije, Hubert Van der Zaag, Pieter Rosbjerg, Dan Aksoy, Hafzullah Viola, Francesco Petrucci, Guido MacLeod, Kit Croke, Barry Ganora, Daniele Hermans, Leon Polo, Maria J. Xu, Zongxue Borga, Marco Helmschrot, Jorg Toth, Elena Ranzi, Roberto Castellarin, Attilio Hurford, Anthony Brilly, Mitija Viglione, Alberto Bloeschl, Guenter Sivapalan, Murugesu Domeneghetti, Alessio Marinelli, Alberto Di Baldassarre, GiulianoPeople Programme (Marie Curie Actions) of the European Union [329762]; IRI THESys; German Excellence Initiative; EU [603587]IW acknowledges the support of the People Programme (Marie Curie Actions) of the European Union's 7th Framework Programme FP7/2007-2013/(grant agreement no. 329762). TK is funded, through IRI THESys, by the German Excellence Initiative. SC, AM, AC, and ET acknowledge financial support from the EU funded project SWITCHON (603587).Taylor & francis ltdAbingdonWe explore how to address the challenges of adaptation of water resources systems under changing conditions by supporting flexible, resilient and low-regret solutions, coupled with on-going monitoring and evaluation. This will require improved understanding of the linkages between biophysical and social aspects in order to better anticipate the possible future co-evolution of water systems and society. We also present a call to enhance the dialogue and foster the actions of governments, the international scientific community, research funding agencies and additional stakeholders in order to develop effective solutions to support water resources systems adaptation. Finally, we call the scientific community to a renewed and unified effort to deliver an innovative message to stakeholders. Water science is essential to resolve the water crisis, but the effectiveness of solutions depends, inter alia, on the capability of scientists to deliver a new, coherent and technical vision for the future development of water systems