Study on estimating the evapotranspiration cover coefficient for stream flow simulation through remote sensing techniques

This study focuses on using remote sensing techniques to estimate the evapotranspiration cover coefficient (CV) which is an important parameter for stream flow. The objective is to derive more accurate stream flow from the estimated CV. The study area is located in the Dan-Shuei watershed in northern Taiwan. The processes include the land-use classification using hybrid classification and four Landsat-5 TM images; the CV estimations based on remote sensing and traditional approaches; comparison of stream flow simulation according to the above two CV values. The result indicated that the study area was classified into seven land-use types with 88.3% classification accuracy. The simulated stream flow using remote sensing approach could represent more accurate hydrological characteristics than a traditional approach. Obviously integrating remote sensing technique and the SEBAL model is a useful approach to estimate the CV. The CV parameter estimated by remote sensing technique did improve the accuracy of the stream flow simulation. Therefore, the results can be extended to further studies such as forest water management.     

Remote sensing and avian influenza: A review of image processing methods for extracting key variables affecting avian influenza virus survival in water from Earth Observation satellites

Recent studies have highlighted the potential role of water in the transmission of avian influenza (AI) viruses and the existence of often interacting variables that determine the survival rate of these viruses in water; the two main variables are temperature and salinity.     

Recent Changes in Land Water Storage and its Contribution to Sea Level Variations

Sea level rise is generally attributed to increased ocean heat content and increased rates glacier and ice melt. However, human transformations of Earth’s surface have impacted water exchange between land, atmosphere, and ocean, ultimately affecting global sea level variations. Impoundment of water in reservoirs and artificial lakes has reduced the outflow of water to the sea, while river runoff has increased due to groundwater mining, wetland and endorheic lake storage losses, and deforestation. In addition, climate-driven changes in land water stores can have a large impact on global sea level variations over decadal timescales. Here, we review each component of negative and positive land water contribution separately in order to highlight and understand recent changes in land water contribution to sea level variations.     

An Assessment of the Accuracy of Triangulated Irregular Networks (TINs) and Lattices in ARC/INFO

This paper evaluates the accuracy of triangulated irregular networks (TINs) and lattices in ARC/INFO. The results of an empirical comparison of the two models over two selected topographic sites are presented. Both vector and raster data were used to build the models. Three pairs of models were constructed based on 1,600, 4,000, and 9,000 sample points for the study area of the State Botanical Garden of Athens, Georgia, and 400, 800, and 1,600 sample points for the study area of Lake Lucerne of Wisconsin. The two models were assessed based on the same number of input sample points. Overall, TINs performed better than lattices. The quality of lattices decreased more dramatically than that of TINs when the number of sample points used for the construction of the models decreased. With an increase in the number of sample points used, the difference in performance between the two models decreased. The results of the evaluation directly depend on the comparison criteria and modeling algorithms. The evaluation is slightly sensitive to test indices used and the distribution of test points. The spatial pattern of residuals on spot heights was quite different from that on randomly selected test points. Users should choose models carefully based on the purpose of their application, the accuracy required, and the computer resources that are available.     

The influence of groundwater representation on hydrological simulation and its assessment using satellite‐based water storage variation

The interaction between surface water and groundwater is an important aspect of hydrological processes. Despite its importance, groundwater is not well represented in many land surface models. In this study, a groundwater module with consideration of surface water and groundwater dynamic interactions is incorporated into the distributed biosphere hydrological (DBH) model in the upstream of the Yellow River basin, China. Two numerical experiments are conducted using the DBH model: one with groundwater module active, namely, DBH_GW and the other without, namely, DBH_NGW. Simulations by two experiments are compared with observed river discharge and terrestrial water storage (TWS) variation from the Gravity Recovery and Climate Experiment (GRACE). The results show that river discharge during the low flow season that is underestimated in the DBH_NGW has been improved by incorporating the groundwater scheme. As for the TWS, simulation in DBH_GW shows better agreement with GRACE data in terms of interannual and intraseasonal variations and annual changing trend. Furthermore, compared with DBH_GW, TWS simulated in DBH_NGW shows smaller decreases during autumn and smaller increases in spring. These results suggest that consideration of groundwater dynamics enables a more reasonable representation of TWS change by increasing TWS amplitudes and signals and as a consequence, improves river discharge simulation in the low flow seasons when groundwater is a major component in runoff. Additionally, incorporation of groundwater module also leads to wetter soil moisture and higher evapotranspiration, especially in the wet seasons.     

Conceptualizations of local knowledge in collaborative environmental governance

A major challenge to integrating local knowledge into collaborative environmental governance processes stems from the underlying differences between positivist science and local knowledge; these differences often result in strong differences of opinion regarding which forms of knowledge are valid in environmental decision-making. Previous research on these issues has mainly focused on the attitudes of scientists towards local knowledge. Studies of the views of local and non-scientific actors regarding their own knowledge are much less common. Through a qualitative case study of water allocation planning in South Australia, we analyzed participants’ conceptualizations of local knowledge and the role of local knowledge in collaborative governance. We found that participants defined local knowledge broadly across a number of dimensions and that many acknowledged variability in the nature and quality of different types of local knowledge. While most recognized the value of local knowledge in supporting technical investigations and developing policies, very few participants identified a role for local knowledge in the early stages of the collaborative process (i.e., in framing problems or establishing research protocols). Previous research has highlighted “epistemological anxiety” among scientists and resource managers toward local knowledge as a significant barrier to its effective use in environmental decision-making. This study suggests that state and local actors, and scientists and non-scientists, share similar reservations about local knowledge and highlights the need for researchers and practitioners to take into account the attitudes of all types of participants when considering how to overcome the epistemological challenges related to integrating local knowledge into collaborative management.     

CO2 Capture and Geologic Storage: The Possibilities

Carbon dioxide (CO₂) capture and geologic storage has been postulated as one possible method to stabilize the atmospheric concentration of CO₂ by injecting and storing it in deep geologic formations. This issue paper analyzes the viability of capture and geologic storage of becoming an effective method to aid in stabilizing the atmospheric concentration of CO₂. It is herein shown that such viability is contingent on overcoming major obstacles that are hydrogeological, technical, and economic in nature. Our analysis indicates that capture and geologic storage is likely to have negligible success in reducing the atmospheric buildup of CO₂ in the coming decades. The magnitude of the anthropogenic emissions of CO₂ indicates that a transition of the world economy away from reliance on fossil fuels might be the only path to stabilize its atmospheric concentration.     

Comparative analysis of different techniques for spatial interpolation of rainfall data to create a serially complete monthly time series of precipitation for Sicily,Italy

The availability of good and reliable rainfall data is fundamental for most hydrological analyses and for the design and management of water resources systems. However, in practice, precipitation records often suffer from missing data values mainly due to malfunctioning of raingauge for specific time periods. This is an important issue in practical hydrology because it affects the continuity of rainfall data and ultimately influences the results of hydrologic studies which use rainfall as input. Many methods to estimate missing rainfall data have been proposed in literature and, among these, most are based on spatial interpolation algorithms.     

Thermochronology of the PoSen complex,northern Vietnam: Implications for tectonic evolution in SE Asia

The PoSen complex, located closely adjacent to the southwestern margin of the Red River shear zone represents the uplifted basement of north Vietnam and may record the motion of the shear zone. However, its thermochronological history has not been fully examined yet. Here we applied U–Pb and ⁴⁰Ar/³⁹Ar dating methods to reveal its thermochronological history. U–Pb analysis of composite zircon grains by TIMS yielded an average age of 760 ± 25 Ma, clustering on the concordia line. Twelve SHRIMP U–Pb analyses also yielded a consistent result of 751 ± 7 Ma. Along with the geochemical features, the U–Pb dating results suggest the PoSen complex was a late Proterozoic magmatic complex, which could correspond to the Chengjiang orogeny, a widespread thermal event in southwest China. Results of ⁴⁰Ar/³⁹Ar dating of micas and K-feldspars were in the range of 36–30 Ma, revealing a rapid cooling and exhumation history of the PoSen complex during the late Paleogene. The time span of cooling and exhumation of the PoSen complex is slightly older than the main cooling phases of the Ailao Shan–Red River (ASRR) metamorphic massifs (28–17 Ma), but is synchronous with the early igneous activity stage in the eastern Indo-Asian collision zone of southeast China and north Vietnam. Owing to the ongoing debate about the initiation and offset of the ASRR shear zone, the tectonic force for the late Paleogene cooling of the PoSen complex is still inconclusive. The rapid exhumation of the PoSen complex could be in response to either the detachment of the Neo-Tethyan slab or a transpressional phase of continental subduction along the ASRR shear system in the eastern Indo-Asian collision zone.