Hydrological Research Letters Vol. 11(2017) No. 3

A strategic analysis of an ongoing brownfield management conflict in Elmira, Ontario, Canada is conducted using the Graph Model for Conflict Resolution. This investigation of the situation as it existed in late 2016 constitutes an expansion of an earlier analysis of the dispute which focused on cleansing the groundwater aquifer, polluted by a chemical company in Elmira, to a controversy over the management of the pollution impacts on an adjacent creek. Besides the chemical plant, the other decision-makers involved in the 2016 dispute are the Ministry of Environment and Climate Change of the Province of Ontario, local government, and a citizens’ advisory group. The connections of the 2016 conflict to the earlier study which took place in 1991 are discussed and the evolution of the previous situation to the current one is explored in depth, along with strategic insights.

The water budget and discharge processes in a seasonal tropical watershed were analyzed. The watershed has very stable base stream flows even in the late dry season and very quick direct runoff during rains. A tentative runoff error correction method applying an existing lumped runoff model was proposed in this paper and showed good agreement with the correct runoff error. After correcting runoff data, the annual average rainfall and runoff during the 11 years of 1998–2008 were calculated respectively as 1870.4 mm and 1229.2 mm. The average annual water loss was 641.2 mm. Distribution measurements of topsoil depth taken using a knocking cone penetration meter showed that this watershed has a deep topsoil layer (5.3 m average). Groundwater tables are apparent only in the lower area of the watershed. A saturated swamp area is a permanent feature near the weir. Results suggest that the stable base flow in this watershed was generated by return flow of soil-water infiltration into the thick topsoil and fractured bedrock.

Formulating countermeasures to flooding risks is important, especially in areas where data are scarce. Numerical modeling techniques may enable hydrologists to model flooding events and access flood risk. Many flooding-inundation models have been developed and successfully applied to many areas. The rainfall-runoff-inundation (RRI) model is one such model that has been applied in various places to estimate river discharges and flooding-inundation depths. However, its applicability to flat river basins is in question. Here, we evaluate the applicability of RRI model to a flat river basin in a data-scarce region. Using the Bago River basin, Myanmar, as a case study, we analyzed past extreme flooding events and developed flooding-inundation maps. The model was calibrated with observed discharge data for a 2011 flooding event and validated for flooding events in 2014 and 2015. The model produced reasonable hydrographs (both peak and base flows). Although the simulated discharges showed good agreement with observed data, the simulated inundation extent showed some discrepancies due to lack of data. Our results indicate that the RRI model may be applicable to flat river basins (short-term analysis). However, for long-term flood simulation, the model may not be the ideal choice as it does not include any land-atmosphere interactions.

The root water uptake profile (RWUP) reflects a plant’s survival strategy and controls evapotranspiration and carbon fluxes. Despite its importance, there is still no reliable method for reconstructing this profile. In this study, we applied and compared two possible approaches to a case study in a conifer plantation: an isotope-calibrated mechanistic model and a mixing model with a bell-shaped approximation. Our results show that, after calibrating the hydrologically-active root density profile, the mechanistic model gave a good estimation of the xylem water isotope delta (δ_x); even though the measured root density was greater in shallower soils, water uptake occurred throughout the entire soil profile, with more uptake in deeper soils. The RWUPs estimated by the mixing model were different from those estimated by the mechanistic model and were unrealistic. However, when we constrained the minimum thickness of the water uptake zone, there was good agreement between the RWUPs from the two approaches. We can therefore conclude that the mechanistic model calibrated with isotopes gave better results, and that sole use of the mixing model is not recommended unless appropriate constraints are applied.

Global warming experiments using high-resolution climate models are important for studying the impact of global warming on human society from region to region. Three different cumulus schemes (YS: Yoshimura, KF: Kain-Fritsch and AS: Arakawa-Schubert) in the high-resolution Meteorological Research Institute AGCM have simulated slightly different future summer mean precipitation changes in East Asia, which are not negligible in the context of regional climate change. Specifically, 25-year mean June-July-August (JJA) average precipitation clearly decreases over eastern Japan, and tends to increase over northern Japan in YS. However, in KF and AS, decreases in precipitation are not significant over Japan, and an increase is clear from central China through southwestern Japan. Addtionally, the increase is extended over the Pacific side of Japan in KF.

The above dependence of future changes in precipitation in East Asia on the scheme used is interpreted by comparing future changes in water and heat balances in the atmosphere. Among possible global warming effects, scheme dependence is attributed to different changes in mean vertical velocity associated with southward shift of the westerly jet over the northern Pacific and weakened Asian monsoon circulations over Eurasia.