Mark Mulligan

Balancing hydropower and biodiversity in the Amazon, Congo, and Mekong

Basin-scale planning is needed to minimize impacts in mega-diverse rivers The worlds most biodiverse river basins—the Amazon, Congo, and Mekong—are experiencing an unprecedented boom in construction of hydropower dams. These projects address important energy needs, but advocates often overestimate economic benefits and underestimate far-reaching effects on biodiversity and critically important fisheries. Powerful new analytical tools and high-resolution environmental data can clarify trade-offs between engineering and environmental goals and can enable governments and funding institutions to compare alternative sites for dam building. Current site-specific assessment protocols largely ignore cumulative impacts on hydrology and ecosystem services as ever more dams are constructed within a watershed (1). To achieve true sustainability, assessments of new projects must go beyond local impacts by accounting for synergies with existing dams, as well as land cover changes and likely climatic shifts (2, 3). We call for more sophisticated and holistic hydropower planning, including validation of technologies intended to mitigate environmental impacts. Should anything less be required when tampering with the worlds great river ecosystems?

A real-time hydrological model for flood prediction using GIS and the WWW

The purpose of this paper is to examine the current status of real time hydrological models used for flood nowcasting and hazard mitigation and indicate how WWW-based systems can overcome some of the limitations of existing systems. Whilst hydrologically innovative and robust models are available, they are poorly suited to real time application, are often not well integrated with spatial datasets such as GIS. Current systems also lack flexibility, customisability and accessibility by a range of end users. We describe the development of a Web-based hydrological modelling system that permits integrated handling of real-time rainfall data from a wireless monitoring network. A spatially distributed GIS-based model is integrated on the basis of this incoming data, approximating real-time to produce data on catchment hydrology and runoff. The data can be accessed from any WWW interface, and they can be analysed online using a number of GIS and numerical functions. We discuss the potential users of such a system and the requirements for interfacing model output with these users for hydrological nowcasting and spatial real-time, emergency decision support. Rather than discuss developments in the modelling of hydrology for flood hazard mitigation, this paper focuses on developments in interfacing these models with end users.

Integrated modelling and decision-support tools: a Mediterranean example

A great deal of new knowledge and research material have been generated from research carried out under the auspices of the European Union (EU). However, only a small amount has been made available as practical policy-support tools. In this paper, we describe how EU funded research models and understanding have been integrated into an interactive decision-support system addressing physical, economic and social aspects of land degradation in the Mediterranean. We summarise the 10 constituent models that simulate hydrology, human influences, crops, natural vegetation and climatic conditions. The models operate on very different spatial and temporal scales and utilise different modelling techniques and implementation languages. Many scientific, modelling and technical issues were encountered during the transformation of ‘research’ models into ‘policy’ models. We highlight the differences between each type of model and discuss some of the ontological and technical problems in re-using research models for policy-support, including resolving differences in temporal scale and some of the software engineering aspects of model integration. The involvement of policy-makers, ‘stakeholders’ and other end-users is essential for the specification of relevant decision-making issues and the development of useful interactive support tools. We discuss the problems of identifying both the decision-makers and the issues they perceive as important, their receptivity to such tools, and their roles in the policy-making process. Finally, we note the lessons learned, the resources needed, and the types of end-users, scientists and mediators required to ensure effective communication, technical development and exploitation of spatial modelling tools for integrated environmental decision-making.

Modelling the geomorphological impact of climatic variability and extreme events in a semi-arid environment

Abstract The climate of the Mediterranean is marginal for many of the economic activities upon which the people of the region depend. Part of this marginality stems from the high inter-annual and medium-term variability in climate. This paper examines the impact of climatic variability on hydrology and vegetation cover using the PATTERN ecosystem model. Significant inter-annual and medium-term variability in the components of the hydrological budget and in vegetation properties and process is apparent in the results. An examination of the variability of soil erosion which results from this variable hydrology and vegetation cover, indicates the temporally erratic nature of erosion events, the tendency for most erosion to occur in very few extreme events, and the dynamic response of erosion to climatic variability. The results also indicate the dependence of erosion on the type of vegetation cover and vegetation response to climatic variability. I conclude with the observation that the majority of significant soil erosion events in Castilla La Mancha (CLM)—site of the EFEDA I and EFEDA II research projects—occur as a result of extreme precipitation events rather than slow progressive land degradation. In this way, soil erosion can be a poor indicator of land degradation. Badlands are the relic of past climatic extremes and not necessarily an indicator of present-day desertification.

On the relationship between a resource based measure of geodiversity and broad scale biodiversity patterns

Geodiversity, (diversity of the geosphere) incorporates many of the environmental patterns and processes that are considered drivers of biodiversity. Components of geodiversity (climate, topography, geology and hydrology) can be considered in terms of their resource giving potential, where resources are taken as energy, water, space and nutrients. The total amount of these resources, along with their spatial and temporal variation, is herein proposed as a compound index of geodiversity that has the potential to model broad scale biodiversity patterns. This paper outlines potential datasets that could be used to represent geodiversity, and then reviews the theoretical links between each element of the proposed compound index of geodiversity (overall resource availability, temporal variation and spatial variation in those resources) and broad-scale patterns of biodiversity. Support for the influence of each of the elements of geodiversity on overall biodiversity patterns was found in the literature, although the majority of relevant research focuses on resource availability, particularly available energy. The links between temporal and spatial variation in resources and biodiversity have been less thoroughly investigated in the literature. For the most part, it was reported that overall resource availability, temporal variation and spatial variation in those resources do not act in isolation in terms of controlling biodiversity. Overall there are sufficient datasets to calculate the proposed compound index of geodiversity, and evidence in the literature for links between the geographical distribution of biodiversity and each of the elements of the compound index defined. Since data for measuring geodiversity is more spatially consistent and widely available (thanks to satellite remote sensing) geodiversity has potential as a conservation planning tool, especially where biological data are not available or sparsely distributed.

Spatial patterns of soil water balance on intensively cultivated hillslopes in a semi-arid environment: the impact of rock fragments and soil thickness.

During past decades, a diverse system of subsistence agriculture in south-east Spain (annual rainfall of less than 300 mm) has been overturned in favour of large-scale plantations of almond trees without consideration for topography and related spatial patterns in soil hydrological properties. The objective of this paper is to investigate the spatial pattern in soil physical properties induced by this cultivation system, and to highlight its impacts on the water balance. Soil properties were recorded along hillslopes with shallow soils developed on slates and greywackes in the upper part of the Guadalentin drainage basin (Murcia region). Frequent tillage of these almond plantations covering entire hillslopes has resulted in denudation by tillage erosion on the topographic convexities, as well as transport of rock fragments and fine earth along the slopes. These processes have created a systematic spatial pattern of soil thickness and rock fragment content: shallow and stony soils on the topographic convexities and deep soils with a rock fragment mulch in the concavities at the foot of the slopes. At the same time, a negative relationship between rock fragment content and fine earth bulk density was observed. The impact of this spatial pattern in soil properties on the water balance was evaluated using the PATTERN one-dimensional hydrological and plant growth model, The model simulates the water balance of soil profiles covering the observed variation in soil thickness, stoniness and bulk density. The model results indicate that the highest rates of infiltration, evaporation and drainage, as well as the lowest rates of overland flow are restricted to shallow soils on the hilltops. In contrast, the deeper soils in the valley bottoms produce a more stable moisture regime than shallower soils, which tend to saturate and dry out quickly. These model results are in agreement with the spatial patterns of almond productivity: an asymptotic increase with soil thickness. Copyright (C) 2000 John Wiley & Sons, Ltd.

Evaluation of precipitation estimation accuracy in reanalyses, satellite products, and an ensemble method for regions in Australia and south and east Asia

Precipitation estimates from reanalyses and satellite observations are routinely used in hydrologic applications, but their accuracy is seldom systematically evaluated. This study used high-resolution gauge-only daily precipitation analyses for Australia (SILO) and South and East Asia [Asian Precipitation—Highly-Resolved Observational Data Integration Towards Evaluation (APHRODITE)] to calculate the daily detection and accuracy metrics for three reanalyses [ECMWF Re-Analysis Interim (ERA-Interim), Japanese 25-yr Reanalysis (JRA-25), and NCEP‐Department of Energy (DOE) Global Reanalysis 2] and three satellite-based precipitation products [Tropical Rainfall Measuring Mission (TRMM) 3B42V6, Climate Prediction Center morphing technique (CMORPH), and Precipitation Estimation from Remotely Sensed Imagery Using Artificial Neural Networks (PERSIANN)]. A depthfrequency-adjusted ensemble mean of the reanalyses and satellite products was also evaluated. Reanalyses precipitation from ERA-Interim in southern Australia (SAu) and northern Australasia (NAu) showed higher detection performance. JRA-25 had a better performance in South and East Asia (SEA) except for the monsoon period, in which satellite estimates from TRMM and CMORPH outperformed the reanalyses. In terms of accuracy metrics (correlation coefficient, root-mean-square difference, and a precipitation intensity proxy, which is the ratio of monthly precipitation amount to total days with precipitation) and over the three subdomains, the depth-frequency-adjusted ensemble mean generally outperformed or was nearly as good as any of the single members. The results of the ensemble show that additional information is captured from the different precipitation products. This finding suggests that, depending on precipitation regime and location, combining (re)analysis and satellite products can lead to better precipitation estimates and,thus, more accurate hydrological applications than selecting any single product.

The hydroclimatic and ecophysiological basis of cloud forest distributions under current and projected climates

BACKGROUND Tropical montane cloud forests (TMCFs) are characterized by a unique set of biological and hydroclimatic features, including frequent and/or persistent fog, cool temperatures, and high biodiversity and endemism. These forests are one of the most vulnerable ecosystems to climate change given their small geographic range, high endemism and dependence on a rare microclimatic envelope. The frequency of atmospheric water deficits for some TMCFs is likely to increase in the future, but the consequences for the integrity and distribution of these ecosystems are uncertain. In order to investigate plant and ecosystem responses to climate change, we need to know how TMCF species function in response to current climate, which factors shape function and ecology most and how these will change into the future. SCOPE This review focuses on recent advances in ecophysiological research of TMCF plants to establish a link between TMCF hydrometeorological conditions and vegetation distribution, functioning and survival. The hydraulic characteristics of TMCF trees are discussed, together with the prevalence and ecological consequences of foliar uptake of fog water (FWU) in TMCFs, a key process that allows efficient acquisition of water during cloud immersion periods, minimizing water deficits and favouring survival of species prone to drought-induced hydraulic failure. CONCLUSIONS Fog occurrence is the single most important microclimatic feature affecting the distribution and function of TMCF plants. Plants in TMCFs are very vulnerable to drought (possessing a small hydraulic safety margin), and the presence of fog and FWU minimizes the occurrence of tree water deficits and thus favours the survival of TMCF trees where such deficits may occur. Characterizing the interplay between microclimatic dynamics and plant water relations is key to foster more realistic projections about climate change effects on TMCF functioning and distribution.

Using learning networks to understand complex systems: a case study of biological, geophysical and social research in the Amazon

Developing high‐quality scientific research will be most effective if research communities with diverse skills and interests are able to share information and knowledge, are aware of the major challenges across disciplines, and can exploit economies of scale to provide robust answers and better inform policy. We evaluate opportunities and challenges facing the development of a more interactive research environment by developing an interdisciplinary synthesis of research on a single geographic region. We focus on the Amazon as it is of enormous regional and global environmental importance and faces a highly uncertain future. To take stock of existing knowledge and provide a framework for analysis we present a set of mini‐reviews from fourteen different areas of research, encompassing taxonomy, biodiversity, biogeography, vegetation dynamics, landscape ecology, earth‐atmosphere interactions, ecosystem processes, fire, deforestation dynamics, hydrology, hunting, conservation planning, livelihoods, and payments for ecosystem services. Each review highlights the current state of knowledge and identifies research priorities, including major challenges and opportunities. We show that while substantial progress is being made across many areas of scientific research, our understanding of specific issues is often dependent on knowledge from other disciplines. Accelerating the acquisition of reliable and contextualized knowledge about the fate of complex pristine and modified ecosystems is partly dependent on our ability to exploit economies of scale in shared resources and technical expertise, recognise and make explicit interconnections and feedbacks among sub‐disciplines, increase the temporal and spatial scale of existing studies, and improve the dissemination of scientific findings to policy makers and society at large. Enhancing interaction among research efforts is vital if we are to make the most of limited funds and overcome the challenges posed by addressing large‐scale interdisciplinary questions. Bringing together a diverse scientific community with a single geographic focus can help increase awareness of research questions both within and among disciplines, and reveal the opportunities that may exist for advancing acquisition of reliable knowledge. This approach could be useful for a variety of globally important scientific questions.

The impact of soil properties and topography on drought vulnerability of rainfed cropping systems in southern Spain

The acreage of rainfed almond plantations (Prunus dulcis (Miller)) in Spain has rapidly increased during the last 30 years, reflecting a tendency towards specialisation in perennial, rainfed crops in many Mediterranean regions. Seminatural vegetation and diverse cropping systems have been converted into monocultures with low tree densities leaving the soil unprotected. This paper illustrates the contrast in water conservation strategies between traditional and modem almond plantations in the Murcia region (Spain), and highlights the impacts of intensification on soil degradation. The role of lateral and vertical redistribution of soil moisture in water conservation will be discussed based on the analysis of soil moisture retention characteristics, temporal variation in soil moisture content and soil moisture patterns. A traditional cereal/almond cropping system typical for mart areas with a subdued relief will be compared to a modem almond monoculture in a highly dissected landscape on slate bedrock. The low water holding capacity of the stony soil in the slate area caused rainfall to penetrate deep in the profile and thus soil moisture fluxes were mainly vertical. Semivariograms of topsoil moisture content after an isolated rain day (19 and 27 mm for the nearest raingauges) demonstrated the differences in lateral redistribution of soil moisture between the cropping systems. A spatial pattern in the mart soil with a range of 69 m was observed, whereas soil moisture in the slate area showed no spatial pattern except for higher values in the narrow valley bottom. The scarcity of rainfall producing lateral redistribution of soil moisture explained the lack of reliable moisture supply in the mart area. This led to very low overall plant densities at 16 trees ha(-1), restricted to wetter zones upstream of retention dams. The redistribution of soil moisture by vertical fluxes in the stony soils of the slate area explained the uniform, widely spaced trees at densities of 204 trees ha(-1). This study has highlighted the need for rainfall to penetrate deep into the soil to sustain almond monocultures in semiarid climates. However, this requires a loose, bare topsoil between the trees and thus large areas of bare soil are exposed on hillslopes resulting in high erosion risks