Using Data on Social Influence and Collective Action for Parameterizing a Geographically-Explicit Agent-Based Model for the Diffusion of Soil Conservation Efforts

Social influence affects individual decision-making on soil conservation. Understanding the emergent diffusion of collective conservation effort is relevant to natural resource management at the river basin level. This study focuses on the effect of subjective norms and collective action on the diffusion of Soil Conservation Effort (SCE) in the Lake Naivasha basin (Kenya) for the period 1965–2010. A geographically-explicit Agent-Based Model (ABM) version of the CONSUMAT model was developed: the CONSERVAT model. In our model, we have represented heterogeneity in the physical environment and in the social network using empirical data. To parameterize the model, physical data, and social data from a household survey (n = 307) were used. Model simulation results show that it is possible to reproduce empirical spatiotemporal diffusion patterns of SCE levels which are quite sensitive to the way in which social survey data are used to initialize the model. Overall, this study demonstrates (i) that social survey data can effectively be used for parameterization of a geographically-explicit ABM, and (ii) that empirical knowledge on natural environment characteristics and social phenomena can be used to build an agent-based model at the river basin level. This study is an important first step towards including subjective norms for evaluating the effectiveness of alternative policy strategies for natural resource management.</p

The Eco-hydrology of Lake Naivasha: A focus on sediment deposition and aggregation to investigate changes in water volume and methods of continual long term monitoring.

Lake Naivasha is an important economic asset for Kenya; it currently supports a growing population, a thriving tourism industry, geothermal energy production and over 60 flower farms which predominantly export to Europe. Recent declines in lake level and water quality have led to a marked increase in scientific studies with a common goal to improve management and conservation. The lake is vulnerable to long, hot periods with low rainfall, which increases evaporation rates resulting in concentrations of pollutants in the water rising. The effect of variations in water quality and availability are both felt locally and internationally. While the flower farms and other abstractive industries are easy to blame for the lakes decline in water level, sediment deposition is, and has been, occurring since the formation of Lake Naivasha. Changes in sediment load and streamflow are indicative of the health of the upper catchment. Upstream land usage has changed from natural forests and open land to farming and anthropogenic uses and due to erosion, riverine loads have increased in recent decades. By using remote sensing and coring, this study sought to identify areas of sediment deposition and quantify recent changes in deposition rates due to upstream erosion events or changes in land-management practices. A novel low-cost and easily replicable remote sensing technique was developed successfully to quantify deposition rates. Sedimentation was found to be most prominent in the northern area of Lake Naivasha at an average of 23 mm yr-1, displacing 308139 m³ of water each year. Current management plans set abstraction quotas using lake level measured in metres above sea level. While long-term fluctuations of lake-levels are consistent or perhaps even increasing, lake volume may in fact be slowly declining. This paper recommends that regular satellite and sonar remote sensing could be key to monitoring the health of the basin as well as effectively improving the management of Lake Naivasha which will ensure the long-term existence of the resource and the population and industry it supports

Reasoning about river basins: WaWO+ revisited

© . This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/This paper characterizes part of an interdisciplinary research effort on Artificial Intelligence (AI) techniques and tools applied to Environmental Decision-Support Systems (EDSS). WaWO+ the ontology we present here, provides a set of concepts that are queried, advertised and used to support reasoning about and the management of urban water resources in complex scenarios as a River Basin. The goal of this research is to increase efficiency in Data and Knowledge interoperability and data integration among heterogeneous environmental data sources (e.g., software agents) using an explicit, machine understandable ontology to facilitate urban water resources management within a River Basin.Peer ReviewedPostprint (author's final draft

Hydro-Economic Modeling of Water Resources Management Challenges: Current Applications and Future Directions

Hydro-economic modeling (HEM) addresses research and policy questions from socioeconomic and biophysical perspectives under a broad range of water-related topics. Applications of HEM include economic evaluations of existing and new water projects, alternative water management actions or policies, risk assessments from hydro-climatic uncertainty (e.g., climate change), and the costs and benefits of mitigation and/or adaptation to such events. This paper reviews applications of HEM in five different categories: (1) climate change impacts and adaptation, (2) water–food–energy–ecosystems nexus management, (3) capability to link to other models, (4) innovative water management options, and (5) the ability to address and integrate uncertainty. We find that (i) the increasing complexity and heterogeneity of water resource management problems due to the growing demand and competition for water across economic sectors, (ii) limited availability and high costs of developing additional supplies, and (iii) emerging recognition and consideration of environmental water demands and value, have inspired new integrated hydro-economic problems and models to address issues of water–food–energy nexus sustainability, resilience, reliability through water (re)allocation based on the relative “value” of water uses. In the past decade, the field of HEM has improved the integration of ecosystem needs, but their representation is still insufficient and mostly ineffective. HEM studies address how to sustainably manage water resources, including groundwater which has become an area of particular interest in climate change adaptation. The current most used spatial and temporal resolutions (basin-scale and yearly time-step) are appropriate for planning but not for operational decisions and could be underestimating impacts from extreme events (e.g., flood risk) captured only by sub-monthly time scales. In addition, HEM primarily focuses on biophysical and economic indicators but often overlooks preferences and perspectives of stakeholders. Lastly, HEM has been widely used to analyze transboundary cooperation, showing benefits for increasing water security and economic development, particularly as climate change develops. We conclude that the field of HEM would benefit from developing more operational models and enhancing the integration of commonly neglected variables, such as social equity components, ecosystem requirements, and water quality

Resilience, collapse and reorganization of a rangeland socio-ecological system in South Africa

Communal rangelands in semi-arid areas are complex socio-ecological systems (SES). Their complexity arises from non-linear feedbacks between the social- and the ecosystem. To understand the social system requires tackling institutional issues associated with common pool resource governance. Moreover, assessing ecosystem dynamics commands to acknowledge high climatic variability in semi-arid areas. This thesis quantifies the dynamics of a communal livestock production SES in a former homeland of South Africa using a SES modelling approach. Here, a social agent based model is combined with a biomass growth model of the rangeland. The coupling of both models is achieved by full integration on software (Java) level. Accordingly, the resulting model does account for ecological complexity. The latter constitutes a contribution to the methodological advancement of bio-economic modelling insofar as bio-economic models strongly simplify ecological processes. The SES model is specified based on primary data from a case study. On a conceptual level, the three main chapters in this thesis investigate aspects of SES resilience, collapse and reorganization. Specifically, chapter two assesses social welfare impacts from reorganizing resource use by the adjustment of stocking rates and alterations of spatio-temporal grazing patterns. Chapter 3 explores the effect of a local norm on SES dynamics with a focus on collapse vs. stability. Finally, chapter 4 quantifies the resilience on multiple scales of the SES towards droughts, a loss of social embededdness and a significant change in subsidization. We found that the adjustment of stocking rates yields higher social benefits compared to the (re)-introduction of rotational grazing in a system assumed to be void of institutional arrangements. In a second step, we identified the existence of a local norm indirectly impacting resource use by endogenous stocking rate adjustments. The existence of the informal institution significantly contributes to the long-term stability of the SES by reducing the chance for collapse. The emergence of norm-following behaviour is fostered by climatic variability. The SES was resilient towards droughts and a change in subsidization. It was however not resilient towards a loss in social embededdness. At another level, only the introduction of a basic income grant was able to stop a process of structural change eroding household resilience. The introduction of a basic income grant enabled poorer households to successfully compete with richer ones without jeopardizing the resilience of the coupled system

Wastewater treatment by a natural wetland: the Nakivubo swamp, Uganda : processes and implications

An investigation to assess the capacity of the Nakivubo swamp, Kampala-Uganda (which has been receiving partially treated sewage from the city for more than 30 years now), to remove nutrients and pathogens was carried out. The aim of the study was to evaluate the potential of this swamp to remove nutrients and pathogens from wastewater in a sustainable way, with emphasis on describing and quantifying their pathways, transformations and budgets.From field studies, water balance terms of channel discharges, rainfall, subsurface flows, evapotranspiration and seiches were measured or calculated from existing hydrometeorological data to form a water balance. Nutrients (N and P) and faecal coliforms (FC) transformations in the swamp were studied from four transects cut across the swamp. Vertical and longitudinal profiles of nutrients and pathogens were also constructed. Laboratory simulations were carried out to estimate nutrient fluxes into the plant and sediment compartments and to estimate the removal mechanisms of FC from the water column.In this study differences in the morphological, hydraulic, physico-chemical, floristic and overall wastewater treatment performance between areas covered by the two major vegetation types Cyperus papyrus L. and Miscanthidium violaceum Robyns (about 80% and 20% of the study area, respectively) were elucidated. Papyrus is emergent at the swamp edges where the water level is more affected by the seasons (rainfall). It floats towards the centre and closer to the lake. The loose rhizomatous raft over which papyrus floats allows for fairly free fall-through of plant debris and decomposing matter onto the sediment via the water column resulting in high suspended solids content in the underlying water. This possibly slows, and sometimes restricts water flow in some areas. Due to the lower flows closer to the edges, a thick (up to 60 cm) layer of peaty material is also formed. The loose mat facilitates vertical mixing between the interstitial mat water and the water beneath the mat during the rise and fall of water/mat levels. This lead to a less steep gradient of nutrients over the vertical profile and facilitates nutrient uptake from the water column by papyrus vegetation.In comparison, Miscanthidium vegetation is restricted to the middle of the swamp and is characterised by a thick (0.9 to 1.6 m) mat with highly interlaced roots, but low bulk density (60 - 300 kg/m 3 , surface to bottom). The thick mat helps the retention of falling plant debris on to its surface, where low rate decomposition and further mat accretion take place. The combination of material retention onto the mat surface and high water flows beneath results into a clearer water column and a very thin peat layer (maximum 10 cm) of poorly decomposed plant material. Further, the mat structure prevents free vertical and lateral mixing of the mat water with the water column beneath. This leads to reduced interactions of the plants with wastewater in these zones, and therefore less nutrient abstraction by plants from the wastewater in these zones.The average waste water discharge in the swamp was estimated at 103,575 m 3 /d. Water flow is highly channelised and hydraulic retention times in the swamp during the rainy periods may be as low as 18 hours. Seepage is negligible. Water quality variations within the swamp showed that wastewater is not evenly transported to all parts of the swamp as it flows through.The nutrient load into the swamp was 770 gN/m 2 /yr and 66 gP/m 2 /yr. Different nutrient uptake rates and plant tissue contents (N=1.3%, P=0.21% for papyrus and N=0.64% and P=0.15% for the Miscanthidium vegetated zones) plus the above structural differences in flows and retention times are partly responsible for the disparate purification efficiencies between the vegetation zones. In the papyrus vegetated zones, the average purification efficiencies were 67% N, and TP and 99.3% FC while in the Miscanthidium vegetated zones, it was lower at 55% N, 33% TP and 89.3% FC. The lower flows (about 20%) that went through the papyrus vegetated zones enabled higher retention times for these zones. The major mechanisms of nutrient removal in papyrus vegetated zones were identified to be plant uptake for the nutrients and attachment onto particulates followed by sedimentation, for FC and P. Predation and natural die-off of FC may be high especially in the root zones where micro-aerobic zones exist (mostly in papyrus zones).The thick mat of Miscanthidium limits the number of live roots that can reach the water column to get nutrients from there. Since the bulk (80% near the lake) of the wastewater goes through this zone, then it means that the overall (swamp-wide) nutrient and pathogen removal efficiency from the wastewater is low (56% N, 40% TP and 91% FC).Very low levels of oxygen were observed in the Nakivubo swamp (and very infrequently) due to the high oxygen demand exerted by decomposing organic matter in the swamp. Mostly, either hypoxic or anoxic conditions existed in most compartments of the swamp limiting nitrification although most physical and chemical variables were the range that would favour the survival of nitrifying bacteria. In the Miscanthidium mat, the low pH also possibly limited the viability and the activity of the nitrifiers in this zone.The sharp decline in the concentration of pollutants from the swamp interface to the open waters of the Inner Murchison Bay can be explained by mixing and dilution in the lake. Combined effects of solar radiation, temperature, pH, biocides and the grazing protozoa may also be responsible for the lower FC numbers.To protect the swamp and use it sustainably, efforts should not only concentrate on halting reclamation but also reducing the loads of effluents/pollutants being discharged into the swamp. Distribution of water over the large expanse of the upper and lower Nakivubo swamps in addition to creating a supplementary buffer system in the form of a forest wetland in the upper are suggested as the best sustainable management options. This should be supplemented with a proper wastewater collection and treatment to at least secondary level within the city

The past : a compass for future earth

Antarctic sea ice impacts on the ocean-atmosphere heat and gas fluxes, the formation of deep and intermediate waters, the nutrient distribution and primary productivity, the so-called &#8216;biological carbon pump&#8217;, one of the most active in the global ocean. In this study, we explore the link between sea ice dynamic, biological production and nutrient cycling during the late Holocene (the last 2,000 yrs) in the Adélie Basin, East Antarctica, from the well-dated sediments of the Ocean Drilling Program (ODP) Site U1357. This archive, composed from ~32 meters of seasonal to annual laminated diatomaceous sequences, allows reconstructions at an unprecedented time resolution (5-10 yrs). Our study combines records of diatom census counts and diatom-specific biomarkers (a ratio (D/T) of di- and tri-unsaturated Highly Branched Isoprenoid lipids (HBI)) as indicators of sea ice and biological production changes, XRF data as markers for terrigenous inputs and bulk nitrogen isotopes (d15N) and d15N on chlorins as proxies for reconstructing nitrogen cycle. The diatom and HBI records reveal five distinct periods. From 0 to 350 yrs AD, decreasing occurrences of sea ice-related diatom species (e.g. Fragilariopsis curta + F. cylindrus) together with low D/T values and increasing open ocean diatom species (large centrics, Chaetoceros Resting Spores (CRS)) document a progressive decline of sea ice presence during the year (>9 months per year) with spring melting occurring earlier in the year and autumn sea ice formation appearing later. In contrast, between 350 and 750 yrs AD, high production of open ocean diatom species and low low D/T values and sea ice related species indicate a short duration of sea ice cover (~10 months per year) is illustrated by a pronounced increase of sea ice-associated diatom species and high D/T values. Between ~1400 and 1850 yrs AD, seasonal sea ice strongly declines (<~7 months per year) as a result of early spring melting (increasing CRS production) and late autumn waxing (high occurrences of Thalassiosira antarctica). Longer growing seasons promoted a substantial development of phytoplankton communities (especially large centric diatoms) that conducted to lower D/T values. Consistent with diatom and HBI reconstructions, XRF data show higher Fe/Al and Zr/Al ratios values during inferred warmer periods and lower ratio values during inferred cooler and icier periods, thus supporting a strong impact of the sea ice seasonal cycle on glacial runoffs. The link between sea ice conditions, biological production and nutrient cycling is still being explored and we will discuss its relationship by combining all the cited records cited above with the d15N records that we are currently generated. Based on our results, we find that sea ice dynamic and associated diatom production in the Adélie Basin revealed an opposite climatic trend than that identified in the Northern Hemisphere for the last 2000 years. The 'Little Ice Age' (1400-1850 yrs AD) or the 'Dark Ages' (400-750 yrs AD) corresponded to warmer climate conditions in the Adélie Basin, while the 'Roman Warm Period' (0-350 yrs AD) or the 'Medieval Warm Period' (900-1200 yrs AD) were associated to colder conditions. We therefore emphasize that Northern and Southern Hemisphere climate evolved in anti-phase seesaw pattern during the late Holocene

Análisis de la asignación sectorial y espacial del agua en la Cuenca del Ebro: impactos de la escasez y las sequías

La gestión sostenible de los recursos hídricos requiere de nuevas políticas basadas en un mejor conocimiento sobre la asignación de los recursos hídricos entre los sectores económicos y el medio natural, y sobre los beneficios que se generan para la sociedad. Este trabajo analiza la distribución espacial y sectorial del agua en la cuenca del Ebro, los efectos de la escasez de agua, y el debate sobre el caudal ecológico en desembocadura. El estudio examina en detalle las zonas de regadío que absorben la mayor parte de los recursos, y las propuestas de caudal ecológico en desembocadura. En el análisis se utiliza un modelo hidroecónomico que simula el impacto de distintas asignaciones espaciales y sectoriales del agua. La adaptación del regadío a la sequía consiste en cambios hacia producciones de mayor rentabilidad económica y tecnologías de riego eficientes. Los resultados muestran que las propuestas de caudal ecológico de la Agencia Catalana del Agua impiden el mantenimiento de las actividades económicas y restringen el desarrollo económico de la cuenca en el futuro. En condiciones de sequía, la propuesta de caudales ecológicos de la Agencia Catalana del Agua de 2007 impediría toda actividad de regadío y cualquier expansión del resto de las actividades económicas de la cuenca. Addressing a more sustainable management of water resources involves new policies that require improved knowledge on water allocations and benefits from the economic and environmental uses of water. This study analyzes the spatial allocation of water resources in the Ebro basin and the distribution by sector, the effects of water scarcity, and the debate on environmental flows in the Ebro mouth. The analysis focus on the irrigated districts using the major share of resources, and on the environmental flows proposals for the River mouth. A hydro-economic model is developed to simulate the effects of different water distribution scenarios by sector and location. Irrigation adaption strategies during drought periods are changes in crop patterns towards more profitable crops and efficient irrigation technologies. Results show that the environmental flow proposals of the Agencia Catalana del Agua hinder the maintenance of economic activities and restrain the economic development of the basin in the future. under drought conditions, the environmental flow proposal of the Agencia Catalana del Agua 2007 will not only eliminate all irrigation in the basin, but also exclude the expansion of water demand for other economic activities