Renaud Quilbé

Are current phosphorus risk indicators useful to predict the quality of surface waters in southern Manitoba, Canada?

Many phosphorus (P) risk indicators have been developed to assess the risk of P loss from agricultural land to surface water. Most of these indicators are designed for land and climates where rainfall-induced erosion of particulate P from sloping landscapes is the main process of P transport. No indicators have been validated in the Canadian Prairies, where P losses are driven by snowmelt-driven runoff over nearly level landscapes and frozen soils. The objective of this project was to evaluate the relationship between water quality data for P from 14 watersheds and three existing P risk indicators for their potential use in the southern Manitoba prairie region of Canada. None of the indicators, including Birr and Mullas P Index, a preliminary P risk indicator for Manitoba, and a preliminary version of Canadas National Indicator of Risk of Water Contamination by Phosphorus, was significantly correlated with mean concentrations of total P in water or P export per hectare. Although erosion risk was a significant factor influencing the value of these indexes, erosion risk was not correlated with either measure of P loss in these watersheds. Several other watershed characteristics, including average soil test P concentrations, livestock density, proportion of land in annual crops, and the lands inherent capability for agricultural production, were strongly correlated with P concentrations in water (r = 0.80***, r = 0.63**, 0.76***, and -0.70**, respectively). Therefore, these types of P risk indicators require modifications to estimate the risk of P loss under the soil, landscape, and climatic conditions of southern Manitoba.

Information technologies in a wider perspective: integrating management functions across the urban–rural interface

Abstract Recent developments in hydroinformatics, namely watershed modeling tools, show potentials in using these information technologies to implement integrated watershed management and, thus, offer to stakeholders comprehensive decision support systems. This paper presents an overview of hydroinformatics as a means to predict impacts of various point and nonpoint (i.e., diffuse) discharges on the water quality and yield of a watershed, and discusses the practical and technical issues related to their role and use within the context of integrated watershed management. Sample applications of a watershed modeling tool, namely GIBSI, are reported to illustrate some of the capabilities of conducting studies such as: (i) establishing environmental load allocations or total maximum daily loads (i.e., the U.S. framework for managing watersheds) and (ii) evaluating pollutant trading assessment studies at the urban–rural interface. Finally, the paper discusses some of the key practical issues that arise at the interface of integrated urban water management (IUWM) and integrated water resources management (IWRM). From a watershed management point of view, this discussion suggests that IWRM should be used to evaluate the overall efficiency of various urban control strategies as well as to compare the benefits of IUWM with some other alternative solutions (e.g., best management practices).

Assessing the Effects of Historical Land Cover Changes on Runoff and Low Flows Using Remote Sensing and Hydrological Modeling

In some parts of the world, watersheds are experiencing changes in land cover that affect their hydrological regime. This paper presents a methodology to assess the potential hydrological response of the Chaudiere River watershed (Quebec) to historical land cover changes. The objectives of this study are: (1) to determine acceptable and plausible land cover scenarios for the past 30 years based on spatial scenario intercomparison and land cover evolution analyses; and (2) to assess the influence of land cover changes on the hydrological regime of the watershed. Historical land cover changes were assessed from seven optical satellite images using an object-oriented approach. Each scenario was entered into GIBSI, an integrated modeling system. Hydrological simulations showed strong correlations between land cover changes and water discharge at the outlet of the watershed. Results demonstrated a homogeneous effect of land cover on annual runoff. Simulated annual and seasonal low flows were also strongly corr...