125 research outputs found
A New Framework of 17 Hydrological Ecosystem Services (HESS17) for Supporting River Basin Planning and Environmental Monitoring
No full textHydrological ecosystem services (HESS) describe the benefits of water for multiple purposes with an emphasis on environmental values. The value of HESS is often not realized because primary benefits (e.g., food production, water withdrawals) get the most attention. Secondary benefits such as water storage, purification or midday temperature cooling are often overlooked. This results in an incorrect evaluation of beneficial water usage in urban and rural resettlements and misunderstandings when land use changes are introduced. The objective of this paper is to propose a standard list of 17 HESS indicators that are in line with the policy and philosophy of the Consultative Group of International Agricultural Research (CGIAR) and that are measurable with earth observation technologies in conjunction with GIS and hydrological models. The HESS17 framework considered indicators that can be directly related to water flows, water fluxes and water stocks; they have a natural characteristic with minimal anthropogenic influence and must be quantifiable by means of earth observation models in combination with GIS and hydrological models. The introduction of a HESS framework is less meaningful without proper quantification procedures in place. Because of the widely diverging management options, the role of water should be categorized as (i) consumptive use (i.e., evapotranspiration and dry matter production) and (ii) non-consumptive use (stream flow, recharge, water storage). Governments and responsible agencies for integrated water management should recognize the need to include HESS17 in water allocation policies, water foot-printing, water accounting, transboundary water management, food security purposes and spatial land-use planning processes. The proposed HESS17 framework and associated methods can be used to evaluate land, soil and water conservation programs. This paper presents a framework that is non-exhaustive but can be realistically computed and applicable across spatial scales
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Developing a locally-tuned method for Earth observation-based forest loss reporting : an ensemble approach to handling uncertainty
No full textDeveloping a dependable forest monitoring system presents a daunting challenge for developing countries that aim to get projects certified by the United Nation’s REDD+ carbon credit program. To help with this goal, many regional and global forest loss products have been developed in recent years that boast a high accuracy level. However, this accuracy only applies to the specific region(s) where the system was developed and this accuracy diminishes outside of these areas. In the country of Cambodia specifically, the most common of these products have an accuracy of 66-70% depending on the region. However developing a local alert system is often not an option due to the large time and money investment required to build and manage one of these systems.
In Chapter 1, low cost options are explored for developing a local alert system, quantifying the amount of reference data needed, defining what factors affect uncertainty, and finally developing a defensible method for tracking disturbance. Using an ensemble architecture, this method utilizes both alert systems and change detection algorithms combined with ancillary factors that contribute to uncertainty to create a higher accuracy map while minimizing costs. By utilizing these inputs with a random forest classifier, we were able to generate maps 10-20% more accurate than those generated by regional alert systems. This high level of accuracy was even maintained when training data collections were reduced to as low as 100 points. This method helps us take advantage of the strengths of these different products, allowing users to create a more dependable forest disturbance map that can be implemented with minimal time and financial costs. This makes forest monitoring systems more accessible for developing countries, increasing both their chances of gaining REDD+ accreditation and their trust in remote sensing based products.
In Chapter 2, the efficacy of this product is compared to reference data provided by our in country partner and the most commonly used earth observation based forest loss product. The GLAD Global Forest Change product is commonly used by REDD+ project managers and journalists alike as it is easily accessible via the Global Forest Watch platform. However, while this regional product performs well at generating the average loss over large areas, accuracy diminishes at smaller scales. We compare this product against our own and to see what product better meets the needs of the land managers at the Keo Seima Wildlife Sanctuary. While neither product ultimately performed well, this points us in the right direction and shows us that these maps need to be further improved before being used to report forest loss. We also assessed the importance of accounting for land management policy when using one of these maps to track a country’s deforestation. Across all maps, despite their disagreement, taking into account the management policies for the different zones of the Keo Seima Wildlife Sanctuary greatly impacted deforestation area estimates. This chapter provides advice for reporters, scientists, and journalists alike that hope to improve the accuracy of their deforestation estimates
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No full textDe begeleider en/of auteur heeft geen toestemming gegeven tot het openbaar maken van de scriptie.
The supervisor and/or the author did not authorize public publication of the thesis.
Measuring fast-temporal sediment fluxes with an analogue acoustic sensor: a wind tunnel study
No full textResearch objective
In this study, we test two passive traps (BEST sampler and MWAC sampler) and one acoustic device (saltiphone) in an aeolian sand wind tunnel to investigate how the experimental setup and the subsequent data processing affect the quantification of the aeolian sand flux.
Type of research: Empirical research
Method of data collection: Wind tunnel experiments
Data comprises:
- Wind velocity
- Mass transport per height for different samplers
- Analogue output of Saltiphone
- Mass measured by balanc
Cross-Cultural Meta-Analyses
No full textIn the enormous collection of cross-cultural data that have been published during the last few decades it is difficult to perceive patterns. There is a clear need for systematizing the vast amount of cross-cultural studies and for developing models that explain cross-cultural differences in psychology. Two methods of cross-cultural meta-analysis can be distinguished. First, the instrument-based method of comparing data for one instrument across countries is suitable for instruments which have been administered in many countries. Second, a domain-based meta-analysis used a thematic domain from which culture-comparative studies are sampled instead of one specific instrument or method
Spatio-temporal variability in accretion and erosion of coastal foredunes in The Netherlands: regional climate and local topography
No full textResearch objective
Investigation of the relation between foredune erosion/accretion in relation to storminess, aeolian transport potential and beach width.
Type of research
The research is a statistical analysis of a long time series of beach profiles. Six sections of the Dutch coast are considered:Noord-Holland, Texel, Vlieland, Terschelling, Ameland, Schiermonnikoog.
Method of data collection
Original data were obtained from other producers: see "calculated from" links.
Relevant parameters were derived from these datasets using simple algorithms.
• From yearly beach profile: beach width, dune volume
• From hourly sea level data: maximum sea level between profile measurements
• From hourly wind data: yearly transport potential for each site, with 4 different upper limits on wind velocity.
Derived data are that were used in this study are provided in separate files:
• beach_and_dune_data.nc: yearly values of beach width and dune volume for all profiles
• max_sea_level_data.nc: yearly maximum sea level between profile measurements
• transport_potential_data.nc: yearly transport potential for each sit
On Spatially Distributed Hydrological Ecosystem Services Bridging the Quantitative Information Gap using Remote Sensing and On spatially distributed hydrological ecosystem services. Bridging the quantitative information gap using remote sensing and hydrological models
No full textOne of the ways in which the CGIAR Research Program on Water, Land and Ecosystems (WLE) addresses the challenge of achieving sustainable growth is by improving our understanding of tradeoffs and synergies related to water, food, environment and energy. Essential to the success of these efforts is the availability of quantitative data on these tradeoffs and synergies, and how they vary across space and time.
Specifically for the countries sharing the Mekong River, WLE Greater Mekong seeks to drive and inform research and dialogue around the rivers of the region. Hydrological EcoSystem Services (HESS) are heavily affected by intensive development across the region, such as the construction of hydropower dams and land use changes - in particular deforestation, urbanization and agricultural intensification. The full extent of such changes in the agro-ecological system is often unknown, and it is a challenge to account for tradeoffs in HESS in policy processes.
As in many other areas of the world, improving governance and management of water resources and associated land and ecosystems in the Greater Mekong region is not only a matter of generating more data. Sharing of knowledge and practices is a key focus of WLE Greater Mekong, which we strive to promote by enhancing the accessibility of valuable information to a wide diversity of regional stakeholders, and promoting dialogue by facilitating the creation of communities of practice.
This white paper demonstrates state-of-the-art methods for assessing different HESS and their tradeoffs under different development scenarios. It explores opportunities for spatial monitoring of HESS and predicting changes under different future scenarios, information that is essential for achieving a balanced and healthy agro-ecological system. By relying on tools in the public domain and leveraging the resulting HESS data through online information platforms, this white paper is an excellent example of current efforts supported by WLE Greater Mekong to stimulate uptake of ecosystem services assessments in decision-making processes
Measurement uncertainties in quantifying aeolian mass flux: evidence from wind tunnel and field site data
No full textThis dataset contains data from two different studies on aeolian sediment transport. The first study was conducted in Dori, Burkina Faso, the second at Ameland, the Netherlands. The first dataset contains data from a degraded (deg), dune and valley site for 11 events. The second dataset contains data of 18 catchers for 6 different events
Measuring aeolian sand transport using acoustic sensors
No full textAcoustic sensors are frequently used to measure aeolian saltation. Different approaches are used to process the signals from these instruments. The goal of this paper is to describe and discuss a method to measure aeolian saltation with acoustic sensors. In a laboratory experiment, we measured the output from an advanced signal processing scheme on the circuit board of the saltiphone. We use a software implementation of this processing scheme to re-analyse data from four miniphones obtained during a field experiment. It is shown that a set of filters remove background noise outside the frequency spectrum of aeolian saltation (at 8. kHz), whereas signals within this frequency spectrum are amplified. The resulting analogue signal is a proxy of the energy. Using an AC pulse convertor, this signal can be converted into a digital and analogue count signal or an analogue energy signal, using a rectifier and integrator. Spatio-temporal correlation between field deployed miniphones increases by using longer integration times for signal processing. To quantify aeolian grain impact, it is suggested to use the analogue energy output, as this mode is able to detect changes in frequency and amplitude. The analogue and digital count signals are able to detect an increase in frequency, but are not able to detect an increase in signal amplitude. We propose a two-stage calibration scheme consisting of (1) a factory calibration, to set the frequency spectrum of the sensor and (2) a standardized drop-test conducted before and after the experiment to evaluate the response of the sensor
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