Regional Catchment Research Articles

Untangling the food web: farm-to-market distances in British Columbia, Canada

One of the stated missions of many farmers' markets and their advocates is to bring consumers closer to their producers, providing enhanced social capital between the two groups, increased loyalty to local food producers and increased economic opportunity to those producers. Most markets also imply an environmental benefit from shopping locally through a reduction in food miles and thus a corresponding reduction in carbon emissions and resource use. To better understand this claim, farm-to-market distances need to be available in a clear, understandable and accessible way. This paper introduces food webs, a graphical representation of the distance travelled and the regional catchment for producers of urban farmers' markets, as demonstrated in British Columbia, Canada. The food webs show farm locations in an easily accessible manner, the degree to which farmers' markets are serving local food producers and the nature of those producers. The results show a large variation in distance travelled to markets and suggest that a critical examination of what “local” means in the context of farmers' market is needed.

Geomorphometric floodplain classification in a hill region of Hungary

A sufficiently detailed floodplain typology is assumed to be useful in the estimation of local flood risk, planning flood control and river restoration measures and for the survey of landscape ecological patterns. Although floodplains are defined by a range of hydrological, geomorphological and geoecological criteria, floodplain classification should start with geomorphometric characterization of stream channels and floodplains in a valley setting. The study areas selected for the geomorphometric analyses are two representative catchments in the hill regions of Southwest-Hungary: the Kapos River, a river of medium size by Hungarian standards (a tributary of the Sió Canal and of the Danube), and a small tributary in the Drava River system, the Bükkösd Stream. For the delimitation and characterization of their floodplains Digital Elevation Models (DEMs), archive military surveys, and topographic maps have been used. The diagnostic parameters selected for the classification are floodplain width, floodplain (or valley floor) slope, valley confinement (expressed by a longitudinal profile index, LPI), channel sinuosity (indicating river mechanism), and valley depth. They have been analyzed in relationship with the distribution of tributary confluences along the river longitudinal profile. Currently, a large majority of watercourses in the region are channelized and some are dammed for fish-ponds, but the present-day floodplains had been built earlier by seminatural streams. Therefore, the classification is based on pre-regulation floodplain conditions (reconstructed from archive sources), which should be target conditions for any future management or restoration efforts. A visual comparison of the distribution of floodplain parameter values along the longitudinal profile shows that the LPI index is a useful tool for the characterization of the floodplain segments. The floodplain types are classified as 1) no floodplain (LPI values are >0.25, mostly >0.5); 2) gradually broadening floodplain (LPI is between 0.1 and 0.25); 3) partially confined floodplain (LPI ranging between 0.05 and 0.1) and 4) mostly unconfined floodplain with bottleneck reaches (LPI fluctuating more widely, from 0.05 to 0.25).

Priority setting in primary health care: a framework for local catchments

Managers and staff in primary health care partnerships in local catchments, particularly in regional areas, are periodically required to work collaboratively to set health priorities. Setting priorities involves making decisions about which health needs are most important and what programs will be funded to address them. There is no universally agreed set of decision-making rules for setting priorities. Dominant approaches prioritise health economics, and have favoured expert knowledge drawn from technical-rational methodologies rather than consumer involvement and community action. However, research reveals that setting priorities is a complex, value laden, contested process buffeted by competing objectives and political interests. As such, an interdisciplinary, collaborative approach is called for. Using reflective practice from a priority setting project for a primary care partnership in a local, regional catchment in Victoria, Australia, a conceptual framework for priority setting is presented that identifies 13 interconnected factors spanning economic, political, policy, epidemiological, moral, evidentiary and evaluative domains. This interdisciplinary framework extends current knowledge about the considerations and trade-offs in setting priorities among collaborating primary health care agencies. It offers a potentially valuable heuristic tool for healthcare decision-makers in rural areas.

Assessing spatial and temporal connectivity between surface water and groundwater in a regional catchment: Implications for regional scale water quantity and quality

It is common for surface water–groundwater interaction assessments to investigate river reaches at a local scale and as discrete individual systems, which are generally classified as connected (gaining and losing type systems) or disconnected (transitional or completely disconnected type systems). While these classifications are valid at any point in space and time, studies often fail to consider how individual river reaches function in the context of the entire regional river system (comprising multiple river reaches) and what implications this can have on water quantity and quality. In this study, spatial and temporal assessments were made in a regional catchment using hydraulic, hydrochemical, and tracer-based techniques to determine the source and loss terms of the river and groundwater system and how their relative magnitude changes along the river from the catchment headwaters towards the sea. Applying an entire regional river system assessment we demonstrate that the state of connection can change along river reaches, as well as take place concurrently at the same location. Water level data, together with salinity and stable isotope results showed that the relatively low salinity of the fresh water river system was maintained in an otherwise saline regional groundwater system by virtue of the lack of saline groundwater inputs in a river with a dominantly losing connectivity state. This losing state was strongly influenced by the high evapotranspiration of the native vegetation. By determining the state of connection between surface water and groundwater and understanding the variable and complex nature of contiguous river reaches of an entire regional river system more appropriate management practices can be employed.

Coupled forest growth-hydrology modelling as an instrument for the assessment of effects of forest management on hydrology in forested catchments

Abstract. The type and intensity of forest management directly influences regional catchment hydrology. Future forest management must optimise the effects of its practices to achieve sustainable management. With scenario analysis of forestry practices, the effects of different forest utilisation strategies on the hydrology of forested catchments can be temporally and spatially quantified. The approach adopted in this study necessitated the development of an interactive system for the spatially distributed modelling of hydrology in relation to forest stand development. Consequently, a forest growth model was used to simulate stand development assuming various forest management activities. Selected simulated forest growth parameters were entered into the hydrological model to simulate water fluxes under different conditions of forest structure. The approach enables the spatially differentiated quantification of changes in the water regime (e.g. increased evapotranspiration). The results of hydrological simulations in the study area, the Oker catchment (northern Harz Mountains), show that forests contribute to the protection of water systems because they have a balancing effect on the hydrological regime. As scenario simulations also suggest, however, forestry practices can also lead to substantial changes in water budgets of forested catchments. The preservation of the hydrological services of forests requires a sustainable and long-term forest conversion on the basis of current management directives for near natural silviculture. Management strategies on basis of moderate harvesting regimes are preferred because of their limited impact on the water budget.

Snow cover analysis in Emilia-Romagna

In this paper we present an operational chain developed in the Emilia-Romagna region (Italy) to monitor snow cover and snow water equivalent (SWE) over the area managed by the Regional Catchment Technical Service. Remote sensing data from medium resolution sensors (MODIS and AVHRR/3) are used as input for snow cover detection algorithms. Hourly weather station measurements are used as input for a snow melt and accumulation model in order to estimate the snow water equivalent. The model reliability is mainly related to the network density of heated rain gauges detecting snow precipitation. The products are disseminated as web bulletins and they are used in monitoring chain and alert for the Civil Protection Agency.

Spatial variations in apparent recharge rate to a montane Paleozoic bedrock aquifer, Appalachian Mountains, United States

Hydrograph separation methods for estimating recharge are not useful in all watersheds, but in this article, the hypothesis is tested that they should be reasonably accurate in montane humid locations where dissipation times for runoff are short. The study area is a montane carbonate/clastic Paleozoic aquifer in the Appalachian Mountains, West Virginia and Virginia. For 1 yr, groundwater discharge was continuously measured at three different stream reaches; each has grossly similar climate, soils, and topography, but differing geology underlying the main stream channels and different stream orientations with respect to structure. One station measured base flow in a strike-parallel stream of moderate length (13.4 km [8.3 mi]); the other two in strike-normal streams of shorter length (2.7 km [1.7 mi]). Pronounced differences were observed in apparent recharge rate between the strike-normal and strike-parallel streams, with the strike-parallel stream similar in apparent recharge to 21 other regional streams, with both large and small catchments, of similar climatic and geologic conditions. Similarly, the strike-normal streams in the study area were significantly lower in recharge compared with these. The precise location of stream losses, if any, could not be pinpointed in detailed streamflow measurements. Although the low apparent recharge rates are primarily ascribed to stream losses, underflow, and/or hyporheic interactions, the evidence for this was nonconclusive. This case underscores that even in humid montane settings of moderate relief, complications in the groundwater budget may arise that make recharge estimates based on surface hydrograph analysis inaccurate.

Lake water changes in response to climate change in northern China: Simulations and uncertainty analysis

Catchment water balance and lake water decline in arid–semiarid areas of China are very sensitive to direct and indirect changes in precipitation and temperature, as evident in written records of the last 50 years and in paleoclimatic records of the past 30,000 years. IPCC-based climate scenarios and outputs of a number of GCM experiments have provided an important basis to configure future climate and to estimate the probability of lake level changes in the next 50 years. However, there are many uncertainties in applying the GCM outputs to regional catchments to evaluate responses at a smaller scale. Monte Carlo probability analysis provides a powerful tool for estimating probability, and this technique was applied to generate scenarios of lake-level responses to future climate change in four arid–semiarid lakes of China. Simulations of Monte Carlo model show that lake level would increase in all sites with precipitation increases, but with temperature increases in Hulun and Aibi basins and with temperature decreases in Qinghai and Daihai basins. With about a 95% chance of a temperature increase in the coming 50 years, the probability of lake water response is about ±50% in Qinghai Basin, +25 ∼ −70% in Daihai Basin, +30% ∼ −20% in Hulun Basin and ±20% in Aibi Basin. Although the predicted future changes of precipitation do not exceed those of the past 30,000 years as estimated from paleorecords, about a 40% annual precipitation change in recent years has caused large lake water decreases and serious drought in the arid basins. Thus, the lower estimate of 20 ∼ 40% decreases of lake level, as estimated with Monte Carlo simulations, seem very probable within the next few decades.

Curve-Number-Based Watershed Model Incorporating Quick Subsurface Runoff, with Applications in the Western Ghats, South India

Wet mountainous watersheds are characterized by variable source area runoff, the runoff generated from surface saturated source areas being the prominent component in most cases. However, often subsurface stormflow, generated by various different mechanisms, also contributes significantly to stream quick flow. The model presented in the present study has been developed to simulate runoff processes in such watersheds, considered to have two quick flow and a delayed flow components. The lumped watershed model used has been developed in stages, starting from the curve-number method, by drawing inferences at every stage and changing the model structure in accordance with the inferences. The data on streamflow and rainfall from five catchments in the Western Ghat regions of Karnataka, in South India, have been used in the study. The simulations of the model have been interpreted to infer that the subsurface pipe flow component forms a very significant part of quick flow in the region.

Range‐Wide Selection of Catchments for Pacific Salmon Conservation

Freshwater ecosystems are declining in quality globally, but a lack of data inhibits identification of areas valuable for conservation across national borders. We developed a biological measure of conservation value for six species of Pacific salmon (Oncorhynchus spp.) in catchments of the northern Pacific across Canada, China, Japan, Russia, and the United States. We based the measure on abundance and life-history richness and a model-based method that filled data gaps. Catchments with high conservation value ranged from California to northern Russia and included catchments in regions that are strongly affected by human development (e.g., Puget Sound). Catchments with high conservation value were less affected by agriculture and dams than other catchments, although only 1% were within biodiversity reserves. Our set of high-value areas was largely insensitive to simulated error, although classification remained uncertain for 3% of catchments. Although salmon face many threats, we propose they will be most likely to exhibit resilience into the future if a complementary mosaic of conservation strategies can be proactively adopted in catchments with healthy salmon populations. Our analysis provides an initial map of where these catchments are likely to be located.

Impact of vegetation coverage on regional water balance in the nonhumid regions of China

The growth of vegetation is affected by water availability, while vegetation growth also feeds back to influence regional water balance. A better understanding of the relationship between vegetation state and water balance would help explain the complicated interactions between climate change, vegetation dynamics, and the water cycle. In the present study, the impact of vegetation coverage on regional water balance was analyzed under the framework of the Budyko hypothesis by using data from 99 catchments in the nonhumid regions of China, including the Inland River basin, the Hai River basin, and the Yellow River basin. The distribution of vegetation coverage on the Budyko curve was analyzed, and it was found that a wetter environment (higher P/E0) had a higher vegetation coverage (M) and was associated with a higher evapotranspiration efficiency (E/E0). Moreover, vegetation coverage was related not only to climate conditions (measured by the dryness index DI = E0/P) but also to landscape conditions (measured by the parameter n in the coupled water–energy balance equation). This suggests that the regional long‐term water balance should not vary along a single Budyko curve; instead, it should form a group of Budyko curves owing to the interactions between vegetation, climate, and water cycle. A positive correlation was found between water balance component (E/P) and vegetation coverage (M) for most of the Yellow River basin and for the Inland River basin, while a negative correlation of M ∼ E/P was found in the Hai River basin. Vegetation coverage was successfully incorporated into an empirical equation for estimating the catchment landscape parameter n in the coupled water–energy balance equation. It was found that interannual variability in vegetation coverage could improve the estimation of the interannual variability in regional water balance.

Late Pleistocene genesis of the middle Yarlung Zhangbo Valley, southern Tibet (China), as deduced by sedimentological and luminescence data

Knowledge on valley formation and palaeohydrology of the Yarlung Zhangbo (named Brahmaputra south of the Himalayas) is still in an early stage. Research was conducted in the middle valley reach around Gonggar in order to investigate the sediment properties, age and palaeoenvironmental implication of a widespread aggradational valley terrace. This heavily dissected terrace, lying c. 25 m above the present floodplain, consists of topping aeolian and colluvial deposits, intermediate lacustrine fines and basal fluvial sands. Sedimentological properties of the lacustrine layers suggest a cold-climate depositional environment. Geochemical data refer to a common provenance of all sediments investigated from a regional catchment area, implying a local provenance of topping loesses and sands by aeolian sorting of nearby fluvial deposits. OSL dates, representing the first luminescence dating effort partly applied to non-aeolian sediments in this valley, cluster closely in the interval 11.7 ± 0.8–17.4 ± 1.4 ka. During the Late Pleistocene (until c. 16 ka) the investigated middle valley reach around Gonggar was occupied by a lake attaining an extension of at least 100 km.

Responses of water yield to changes in vegetation at a temporal scale

The effect of vegetation on the water recycling of a land ecological system is considerably significant. Understanding the relationship between vegetation and runoff changes will benefit regional eco-environmental and water resources management. Based on paired catchments and time trend studies, a number of studies had been undertaken to establish the relationship between vegetation cover and water yield. We obtained some results from paired watersheds by focusing on changes at various time scales. At the mean annual scale the runoff changes resulting from vegetation alteration can be predicted using Zhang’s curves. The absolute change of runoff due to vegetation alteration in a humid area is larger than that in the dry region, while the relative change is reverse. At the annual scale, it takes 15-20 years or longer in the arid region for catchments to reach a new equilibrium after afforestation, and under natural restoration, it takes about a hundred years. The vegetation changes have a proportionally larger impact on low flow at the seasonal scale. For catchments in arid regions, relative changes in low flow sections of the flow duration curve will be much more significant compared with that in the high flow section, leading to increased number of zero-flow days. However, in humid regions, changes in runoff tend to be much more uniform.

Effects of a drought period on physico-chemical surface water quality in a regional catchment area

Hydrological drought periods are expected to become more severe in North-Western Europe as a result of climate change. This may have implications for water quality, as demonstrated by declining water quality of large rivers (e.g. Rhine, Meuse) during droughts. However, similar investigations in regional catchment areas are lacking to date. In the present study, we investigated the effects of a drought period on the water quality of the Dommel River, a tributary of the Meuse river in the Netherlands. Water quality during the drought of 2003 was compared to that in reference years (2004-2006) for 18 physical/chemical parameters using ANOVA analysis. It was demonstrated that the drought period of 2003 did not significantly affect water quality, although the origin of river flow during the drought shifted from mainly overland flow to deep groundwater flow and (treated) communal effluents. Significant differences in water quality were noted for some monitoring stations during the study period, which could be related to operational water management such as cleaning of sediment traps in the river and improvements in communal effluent treatment. The results of this study are interesting to water managers in Western Europe as they contribute to understanding the potential impact of climate change on water quality/quantity patterns in regional water systems.

Processes of attenuation of dissolved arsenic downstream from historic gold mine sites, New Zealand

Mine and processing sites in the mesothermal gold deposits of the Reefton gold field, New Zealand, generate extremely high dissolved As concentrations (up to 59 mg/L). Attenuation of these waters takes place by at least one of the three mechanisms: (1) precipitation of the secondary arsenic mineral scorodite, (2) chemisorption onto iron oxyhydroxide (HFO) and (3) dilution with regional catchment water. The presence and effectiveness of these mechanisms vary among the three studied catchments. A strong physiochemical control on arsenic attenuation was identified due to a chemical gradient within the gold field itself and processing methods, which can generate site specific arsenic minerals, such as arsenolite. Precipitation of scorodite only occurs in the presence of dissolving arsenolite, which is a roasting by-product present at two of the studied sites. Abundant HFO is generated in the pyritic mesothermal part of the gold field, and here chemisorption onto HFO is the dominant attenuation process. In the non-pyritic part of the gold field, HFO is mainly produced as a result of ankerite dissolution but only where sufficiently exposed mineralised rock is present. In the absence of significant adsorption sites, dissolved As is attenuated only via less effective dilution and ecosystem guidelines are exceeded over kilometres downstream from the mineralised zone until drainage waters are diluted by regional catchment water. Catchment morphology was identified as a major control on dilution. Despite the presence of strong As point sources upstream, mine-related As contributes < 10% to the regional As river load in all three catchments. On a regional scale As mobility across a wide range of pH regimes reveals a strong control of scorodite, which has already been observed locally.

Multiobjective training of artificial neural networks for rainfall‐runoff modeling

This paper presents results on the application of various optimization algorithms for the training of artificial neural network rainfall‐runoff models. Multilayered feed‐forward networks for forecasting discharge from two mesoscale catchments in different climatic regions have been developed for this purpose. The performances of the multiobjective algorithms Multi Objective Shuffled Complex Evolution Metropolis–University of Arizona (MOSCEM‐UA) and Nondominated Sorting Genetic Algorithm II (NSGA‐II) have been compared to the single‐objective Levenberg‐Marquardt and Genetic Algorithm for training of these models. Performance has been evaluated by means of a number of commonly applied objective functions and also by investigating the internal weights of the networks. Additionally, the effectiveness of a new objective function called mean squared derivative error, which penalizes models for timing errors and noisy signals, has been explored. The results show that the multiobjective algorithms give competitive results compared to the single‐objective ones. Performance measures and posterior weight distributions of the various algorithms suggest that multiobjective algorithms are more consistent in finding good optima than are single‐objective algorithms. However, results also show that it is difficult to conclude if any of the algorithms is superior in terms of accuracy, consistency, and reliability. Besides the training algorithm, network performance is also shown to be sensitive to the choice of objective function(s), and including more than one objective function proves to be helpful in constraining the neural network training.

Landscape influences on stream fish assemblages across spatial scales in a northern Great Plains ecoregion

We examined the relationship between multiple spatial scales of fish assemblage structure and land cover in streams of a northern Great Plains ecoregion. We used regional richness measurements, an index of biotic integrity (IBI), and nonmetric multidimensional scaling (NMS) ordination to characterize fish assemblages. These metrics were related to regional catchment landscape at two spatial scales (overall catchment, overall riparian) and then to a set of local subcatchments from within these catchments at three scales (overall subcatchment, overall riparian buffer, and reach). Relationships between catchment fish richness, IBI scores, and landscape predictors were strongest at the riparian scale, with the strongest single predictor being riparian forest (r2 = 0.63, P &lt; 0.01). NMS ordination analysis showed clear similarities between fish species assemblages in agriculturally dominated catchments and assemblages found in smaller headwater streams. At the same time, forested catchments and catchments with larger areas exhibited similar fish species assemblages. Our results indicate that both local and regional stream fish assemblages are structured by broader-scale landscape characteristics, with land cover providing a better indication of overall available habitat volume than catchment area or stream order.

Comparison and evaluation of regional climate scenarios for hydrological impact analysis: General scheme and application example

AbstractWe present a scheme and application example for evaluating simulations of possible future conditions of regional climate (‘regional climate change scenarios’) concerning their suitability for hydrological impact studies. The procedure is based on expert knowledge about the impacts of anthropogenic climate change on varying hydrological processes and different hydrological catchment status. A method to evaluate regional climate change scenarios for hydrological impact analysis is presented first, which consists basically of a two‐step knowledge‐based decision and evaluation procedure. The first step (‘climatic evaluation’) evaluates the capability of the climate scenarios to represent regional climate and the plausibility of the future climate conditions. The first step establishes the basis for the second step (‘hydrological evaluation’), which evaluates hydrologically relevant information of the climate scenarios to qualify information about the hydrological processes possibly altered by climate change. From this evaluation of the hydrological processes, an evaluation of regional catchment conditions is derived, such as long‐term water availability, drought conditions or floods.In the second part of the paper, this method is applied systematically to three different regional climate change scenarios, which have been provided for south Germany. This evaluation results in different levels of adequacy, depending on the hydrological process under question. In general, processes which are governed by temperature conditions (e.g. evaporation, snowmelt) are evaluated as ‘more useful’ than the processes governed by precipitation characteristics (e.g. runoff generation, floods). All regional climate change scenario methods investigated are of rather limited value for extreme hydrological conditions. The proposed method can serve to systematically evaluate the usefulness of climate change scenarios for hydrological impact analysis. It becomes apparent that regional climate scenarios should only be applied for hydrological application if the spatial‐temporal scale of variations of the governing hydrological processes is represented by the scenarios. Copyright © 2007 Royal Meteorological Society

Modeling the mechanisms that control in‐stream dissolved organic carbon dynamics in upland and forested catchments

We present a new, process‐based model of soil and stream water dissolved organic carbon (DOC): the Integrated Catchments Model for Carbon (INCA‐C). INCA‐C is the first model of DOC cycling to explicitly include effects of different land cover types, hydrological flow paths, in‐soil carbon biogeochemistry, and surface water processes on in‐stream DOC concentrations. It can be calibrated using only routinely available monitoring data. INCA‐C simulates daily DOC concentrations over a period of years to decades. Sources, sinks, and transformation of solid and dissolved organic carbon in peat and forest soils, wetlands, and streams as well as organic carbon mineralization in stream waters are modeled. INCA‐C is designed to be applied to natural and seminatural forested and peat‐dominated catchments in boreal and temperate regions. Simulations at two forested catchments showed that seasonal and interannual patterns of DOC concentration could be modeled using climate‐related parameters alone. A sensitivity analysis showed that model predictions were dependent on the mass of organic carbon in the soil and that in‐soil process rates were dependent on soil moisture status. Sensitive rate coefficients in the model included those for organic carbon sorption and desorption and DOC mineralization in the soil. The model was also sensitive to the amount of litter fall. Our results show the importance of climate variability in controlling surface water DOC concentrations and suggest the need for further research on the mechanisms controlling production and consumption of DOC in soils.

Closure to “Regional Flood Frequency Analysis Using L-Moments for North Brahmaputra Region of India” by Rakesh Kumar and Chandranath Chatterjee

Closure to “Regional Flood Frequency Analysis Using L-Moments for North Brahmaputra Region of India” by Rakesh Kumar and Chandranath Chatterjee