Estimates of spatial variation in evaporation using satellite‐derived surface temperature and a water balance model

Evaporation dominates the water balance in arid and semi‐arid areas. The estimation of evaporation by land‐cover type is important for proper management of scarce water resources. Here, we present a method to assess spatial and temporal patterns of actual evaporation by relating water balance evaporation estimates to satellite‐derived radiometric surface temperature. The method is applied to a heterogeneous landscape in the Krishna River basin in south India using 10‐day composites of NOAA advanced very high‐resolution radiometer satellite imagery. The surface temperature predicts the difference between reference evaporation and modelled actual evaporation well in the four catchments (r² = 0·85 to r² = 0·88). Spatial and temporal variations in evaporation are linked to vegetation type and irrigation. During the monsoon season (June–September), evaporation occurs quite uniformly over the case‐study area (1·7–2·1 mm day^?1), since precipitation is in excess of soil moisture holding capacity, but it is higher in irrigated areas (2·2–2·7 mm day^?1). In the post‐monsoon season (December–March) evaporation is highest in irrigated areas (2·4 mm day^?1). A seemingly reasonable estimate of temporal and spatial patterns of evaporation can be made without the use of more complex and data‐intensive methods; the method also constrains satellite estimates of evaporation by the annual water balance, thereby assuring accuracy at the seasonal and annual time‐scales. Copyright © 2007 John Wiley & Sons, Ltd.     

Arctic versus temperate comparison of risk assessment metrics for 2-methyl-naphthalene

Reliable risk assessment approaches for Arctic environments are requested to manage potential impacts associated with increased activities in Arctic regions. We performed toxicity tests on Arctic and temperate species exposed to the narcotic acting oil component, 2-methyl naphthalene. The experimental results were used to quantify concentration causing lethality to 50% of exposed individuals and no-effect concentration (individual level). For estimates at community level, the hazardous concentrations affecting 5% and 50% of the species were calculated from sensitivity distribution curves. These survival metrics were then used to elucidate whether temperate toxicity data used in risk assessment are sufficiently representative for the Arctic. Taking data uncertainty into consideration, we found no regional difference in tolerances to 2-methyl naphthalene either at the species level or at the community level. Hence these data support a conclusion that values of survival metrics for temperate regions are transferrable to the Arctic for the chemical 2-methyl naphthalene, as long as extrapolation techniques are properly applied and uncertainties are taken into consideration.     

P-T paths and tectonic evolution of shear zones separating high-grade terrains from cratons: examples from Kola Peninsula (Russia) and Limpopo Region (South Africa)

Summary ?The petrology and P-T evolution of mica schists from two regional scale tectonic (shear) zones that separate high grade terrains (“mobile belts”) from cratons are described. These are the 2.4–1.9 Ga Tanaelv Belt, a suture zone that separates the Lapland granulite complex from the Karelian craton (Kola Peninsula–Fennoscandia), and the 2.69 Ga Hout River Shear Zone that separates the > 2.9 Ga Kaapvaal craton from the 2.69 Ga South Marginal Zone of the Limpopo high-grade terrain (South Africa). Two metamorphic zones are identified in strongly deformed mica schists from the 1.9 Ga Korva Tundra Group of the Tanaelv belt: (1) a chlorite-staurolite zone tectonically overlaying gneisses of the Karelian craton, and (2) a kyanite-biotite zone tectonically underlying garnet amphibolites of the Tanaelv Belt, which are in tectonic contact with the Lapland granulite complex. The prograde reaction Chl+St+Ms ↠ Ky+Bt+Qtz+H₂O clearly defines a boundary between zones (1) and (2). Rotated garnet porphyroblasts from zone (1) contain numerous inclusions (Otz, Chl, Ms), and show clear Mg/Fe chemical zoning, suggesting garnet growth during prograde metamorphism. The metamorphic peak, T = 650°C and P = 7.5 kbar, is recorded in the kyanite-biotite zone and characterized by unzoned snowball garnet. In many samples of mica schists euhedral garnet porphyroblasts of the retrograde stage are completely devoid of mineral inclusions while N _Mg decreases from core to rim, indicating a decrease in P-T from 650°C, 7.5 kbar to 530°C, 5 kbar. The Hout River Shear Zone (South Africa) shows metamorphic zonation from greenschists through epidote amphibolites to garnet amphibolites. Rare strongly deformed mica schists (Chl+Grt+Pl+Ms+Bt+Qtz) occur as thin layers among epidote-amphibolites only. Garnet porphyroblasts in the schists are similar to that of the Tanaelv Belt recording a prograde P-T path with peak conditions of T = 600°C and P∼ 5.5 kbar. The retrograde stage is documented by the continuous reaction Prp+2Ms+Phl ↠ 6Qtz+3East recording a minimum T = 520°C and P ∼ 3.3 kbar. Similar narrow clock-wise P-T loops recorded in mica schists from both studied shear zones suggest similarities in the geodynamic history of both shear zones under consideration.

---

Zusammenfassung ?P-T Pfade und tektonische Entwicklung von Scherzonen, die hochgradige Terranes von Kratonen trennen: Zwei Beispiele von der Halbinsel Kola (Russland) und der Limpopo-Region (Südafrika) Die Petrologie und P-T Entwicklung von Glimmerschiefern aus zwei regionalen tektonischen Scherzonen, die hochgradige Terranes (“mobile belts”) von Kratonen trennen, werden beschrieben. Diese sind der 2.4−1.9 Ga Tanaev Belt, eine Suturzone, die die Lappland Granulite vom karelischen Pluton (Halbinsel Kola - Fennoskandien) trennt, sowie die 2.69 Ga Hout River Shear Zone, die den > 2.9 Ga Kaapvaal Kraton von der 2.69 Ga South Marginal Zone des hochgradigen Limpopo Terranes (Südafrika) trennt. Zwei metamorphe Zonen sind in stark deformierten Glimmerschiefern der 1.9 Ga Korva Tundra Group zu unterscheiden: (1) eine Chlorit-Staurolith-Zone, die den Gneisen des karelischen Kratons auflagert, und (2) eine Kyanit-Biotit-Zone, die die Granatamphibolite des Tanaev Belt unterlagert und in tektonischem Kontakt mit dem Lappland Granulitkomplex steht. Die prograde Reaktion Chl+St+Ms ↠ Ky+Bt+Qtz+H₂O trennt die beiden Zonen. Rotierte Granatporphyroblasten aus der Zone (1) enthalten zahlreiche Einschlüsse (Qtz, Chl, Ms) und zeigen eine Mg/Fe Zonierung, die Granatwachstum w?hrend des prograden Metamorphosestadiums nahelegen. Der Metamorphoseh?hepunkt (650°C, 7.5 kbar) wurde in der Kyanit-Biotit-Zone erreicht und ist durch nicht zonierte Schneeballgranate charakterisiert. In vielen Glimmerschieferproben sind die euhedralen Granatporphyroblasten des retrograden Stadiums vollkommen einschlu?frei und N _Mg nimmt vom Kern zum Rand hin ab. Das zeigt eine Abnahme der P-T Bedingungen von 650°C, 7.5 kbar auf 530°C, 5 kbar an. Die Hout River Shear Zone in Südafrika zeigt eine metamorphe Zonierung von Grünschiefern, über Epidotamphibolite zu Granatamphiboliten. Selten kommen stark deformierte Glimmerschiefer (Chl+Grt+Pl+Ms+Bt+Qtz) als dünne Lagen zwischen den Epidotamphiboliten vor. Die Granatporphyroblasten sind ?hnlich wie die aus dem Tanaev Belt und belegen eine prograde P-T Entwicklung mit Peak-Bedingungen von 600°C und ≈ 5.5 kbar. Das retrograde Stadium ist durch die kontinuierliche Reaktion Prp+2Ms+Phl ↠ 6Qtz+3East mit minimal 530°C und ≈ 3.3 kbar dokumentiert. Die sehr ?hnlichen P-T Pfade der Glimmerschiefer belegen ?hnlichkeiten in der geodynamischen Geschichte der beiden bearbeiteten Scherzonen.

---

---

Received January 29, 1999;/revised version accepted August 10, 1999     

Climate change impacts on pricing long-term flood insurance: A comprehensive study for the Netherlands

Recently long-term flood insurance contracts with a duration of 5, 10 or 15 years have been proposed as a solution for covering flood risk and mitigating increasing flood losses. Establishing a long-term relation between the policyholder and the insurer can provide better incentives to reduce risk through undertaking damage mitigation measures. However, the uncertainty about the development of future flood risk in the face of climate and socio-economic change may complicate insurers’ rate-setting of long-term contracts. This issue has been examined in this study by estimating the effects of these changes on flood risk and pricing flood insurance premiums of short- and long-term flood insurance contracts in all (53) dike-ring areas in the Netherlands. A broad range of simulations with hydrological and flood damage models are used to estimate the future development of flood risk and premiums. In addition, the long-term development of insurance funds is estimated with a spatial “Climate Risk Insurance Model (CRIM)” for a private insurance arrangement and for a ‘three-layered’ public-private insurance program. The estimation of flood insurance premiums of long-term insurance contracts reveals fundamental problems. One is that there is an incentive for either the consumer or the insurer to prefer short-term rather than long-term contracts in the face of climate-related uncertainty. Therefore, it seems advisable to examine the introduction of one-year flood insurance contracts in the Netherlands, at least until the large uncertainties with climate and socio-economic change on flood risk have been resolved. The estimations performed with the Climate Risk Insurance Model indicate that a private insurance fund could have difficulties with building up enough financial reserves to pay for flood damage, while the layered public-private insurance scheme is more robust.     

Using simulated annealing for resource allocation

Many resource allocation issues, such as land use- or irrigation planning, require input from extensive spatial databases and involve complex decisionmaking problems. Spatial decision support systems (SDSS) are designed to make these issues more transparent and to support the design and evaluation of resource allocation alternatives. Recent developments in this field focus on the design of allocation plans that utilise mathematical optimisation techniques. These techniques, often referred to as multi-criteria decision-making (MCDM) techniques, run into numerical problems when faced with the high dimensionality encountered in spatial applications. In this paper we demonstrate how simulated annealing, a heuristic algorithm, can be used to solve high-dimensional non-linear optimisation problems for multi-site land use allocation (MLUA) problems. The optimisation model both minimises development costs and maximises spatial compactness of the land use. Compactness is achieved by adding a non-linear neighbourhood objective to the objective function. The method is successfully applied to a case study in Galicia, Spain, using an SDSS for supporting the restoration of a former mining area with new land use.     

Mesozoic to Cenozoic tectono‐metamorphic history of the South Pamir–Hindu Kush (Chitral,NW Pakistan): Insights from phase equilibria modelling,and garnet–monazite petrochronology

The Karakoram–Hindu Kush–Pamir and adjacent Tibetan plateau belt comprise a series of Gondwana‐derived crustal fragments that successively accreted to the Eurasian margin in the Mesozoic as the result of the progressive Tethys ocean closure. These domains provide unique insights into the thermal and structural history of the Mesozoic to Cenozoic Eurasian plate margin, which are critical to inform the initial boundary conditions (e.g. crustal thickness, structure and thermo‐mechanical properties) for the subsequent development of the large and hot Tibetan–Himalaya orogen, and the associated crustal deformation processes. Using a combination of microstructural analyses, thermobarometry modelling and U–Th–Pb monazite and Lu–Hf garnet geochronology, the study reappraises the metamorphic history of exposed mid‐crustal metapelites in the Chitral region of the South Pamir–Hindu Kush (NW Pakistan). This study also demonstrates that trace elements in monazite (especially Y and Dy), combined with thermodynamical modelling and Lu–Hf garnet dating, provides a powerful integrated toolbox for constraining long‐lived and polyphased tectono‐metamorphic histories in all their spatial and temporal complexity. Rocks from the Chitral region were progressively deformed and metamorphosed at sub‐ and supra‐solidus conditions through at least four distinct episodes from the Mesozoic to the Cenozoic. Rocks were first metamorphosed at ~400–500°C and ~0.3 GPa in the Late Triassic–Early Jurassic (210–185 Ma), likely in response to the accretion of the Karakoram during the Cimmerian orogeny. Pressure and temperature subsequently increased by ~0.3 GPa and 100°C in the Early‐ to Mid Cretaceous (140–80 Ma), coinciding with the intrusion of calcalkaline granitic plutons across the Karakoram and Pamir regions. This event is interpreted as the record of crustal thickening and the development of a proto‐plateau within the Eurasian margin due to a long‐lived episode of slab flattening in an Andean‐type margin. Peak metamorphism was reached in the Late Eocene–Early Oligocene (40–30 Ma) at conditions of 580–600°C and ~0.6 GPa and 700–750°C and 0.7–0.8 GPa for the investigated staurolite schists and sillimanite migmatites respectively. This crustal heating up to moderate anatexis likely resulted in the underthrusting of the Indian plate after a NeoTethyan slab‐break off or to the Tethyan Himalaya–Lhasa microcontinent collision and subsequent oceanic slab flattening. Near‐isothermal decompression/exhumation followed in the Late Oligocene (28–23 Ma) as marked by a pressure decrease in excess of ~0.1 GPa. This event was coeval with the intrusion of the 24 Ma Garam Chasma leucogranite. This rapid exhumation is interpreted to be related to the reactivation of the South Pamir–Karakoram suture zone during the ongoing collision with India. The findings of this study confirm that significant crustal shortening and thickening of the south Eurasian margin occurred during the Mesozoic in an accretionary‐type tectonic setting through successive episodes of terrane accretions and probably slab flattening, transiently increasing the coupling at the plate interface. Moreover, they indicate that the south Eurasian margin was already hot and thickened prior to Cenozoic collision with India, which has important implications for orogen‐scale strain‐accommodation mechanisms.     

Did tillage erosion play a role in millennial scale landscape development?

Landscape evolution models (LEMs) quantitatively simulate processes of sedimentation and erosion on millennial timescales. An important aspect of human impact on erosion is sediment redistribution due to agriculture, referred to herein as tillage erosion. In this study we aim to analyse the potential contribution of tillage erosion to landscape development using LEM LAPSUS. The model is calibrated separately for a water erosion process (i) without tillage and (ii) with tillage. The model is applied to the ~250 km² Torrealvilla case study catchment, SE Spain. We were able to simulate alternating sequences of incision and aggradation, that are important on longer (millennial) timescales. Generally, model results show that tillage erosion adds to deposition in the lower floodplain area, but neither water erosion alone nor water with tillage erosion together could exactly reproduce the observed amounts of erosion and sedimentation for the case study area. In addition, scale effects are apparent. On hillslopes, tillage may contribute importantly to erosion and may fill local depressions. If assessed on the catchment scale, sediments from tillage erosion eventually reach the lower floodplain area where they contribute to deposition. However, water erosion was observed in the model simulations to be the most important process on the catchment scale. This is the first time that tillage erosion has been explicitly included in a landscape evolution model at a millennial timescale and large catchment scale. Copyright © 2012 John Wiley & Sons, Ltd.     

Development of a sustainable livelihood security model for storm-surge hazard in the coastal areas of Bangladesh

Coastal communities in Bangladesh are at great risk due to frequent cyclones and cyclone induced storm-surges, which damages inland and marine resource systems. In the present research, seven marginal livelihood groups including Farmers, Fisherman, Fry (shrimp) collectors, Salt farmers, Dry fishers, Forest resource extractors, and Daily wage labourers are identified to be extremely affected by storm- surges in the coastal area of Bangladesh. A livelihood security model was developed to investigate the security status of the coastal livelihood system in a participatory approach. In the model, livelihood security consists of five components: (1) Food, (2) Income, (3) Life & health, (4) House & properties, and (5) Water security. Analytical hierarchy process was followed to assess the livelihood security indicators based on respondents’ security options. The model was verified through direct field observation and expert judgment. The Livelihood Security Model yields a Livelihood Security Index which can be used for assessing and comparing the household security level (in %) of different livelihood groups in the storm-surge prone coastal areas. The model was applied with data from two major coastal areas (Cox’s Bazar and Satkhira) of Bangladesh and is applicable to other coastal areas having similar settings.     

P–T conditions of decompression of the Limpopo high-grade terrane: record from shear zones

The Southern Marginal Zone of the late Archean Limpopo Belt of southern Africa is an example of a high‐grade gneiss terrane in which both upper and lower crustal deformational processes can be studied. This marginal zone consists of large thrust sheets of complexly folded low‐strain gneisses, bound by an imbricate system of kilometre‐wide deep crustal shear zones characterized by the presence of high‐strain gneisses (‘primary straight gneisses’). These shear zones developed during the decompression stage of this high‐grade terrane. Low‐ and high‐strain gneisses both contain similar reaction textures that formed under different kinematic conditions during decompression. Evidence for the early M1/D1 metamorphic phase (> 2690 Ma) is rarely preserved in low‐strain gneisses as a uniform orientation of relict Al‐rich orthopyroxene in the matrix and quartz and plagioclase inclusions in the cores of early (M1) Mg‐rich garnet porphyroblasts. This rare fabric formed at > 820 °C and > 7.5 kbar. The retrograde M2/D2 metamorphic fabric (2630–2670 Ma) is well developed in high‐strain gneisses from deep crustal shear zones and is microscopically recognized by the presence of reaction textures that formed synkinematically during shear deformation: M2 sigmoid‐shaped reaction textures with oriented cordierite–orthopyroxene symplectites formed after the early M1 Mg‐rich garnet porphyroblasts, and syn‐decompression M2 pencil‐shaped garnet with oriented inclusions of sillimanite and quartz formed after cordierite under conditions of near‐isobaric cooling at 750–630 °C and 6–5 kbar. The symplectites and pencil‐shaped garnet are oriented parallel to the shear fabric and in the stretching direction. Low‐strain gneisses from thrust sheets show similar M2 decompression cooling and near‐isobaric cooling reaction textures that formed within the same P–T range, but under low‐strain conditions, as shown by their pseudo‐idioblastic shapes that reflect the contours of completely replaced M1 garnet and randomly oriented cordierite–orthopyroxene symplectites. The presence of similar reaction textures reflecting low‐strain conditions in gneisses from thrust sheets and high‐strain conditions in primary straight gneisses suggests that most of the strain during decompression was partitioned into the bounding shear zones. A younger M3/D3 mylonitic fabric (< 2637 Ma) in unhydrated mylonites is characterized by brittle deformation of garnet porphyroclasts and ductile deformation of the quartz–plagioclase–biotite matrix developed at < 600 °C, as the result of post‐decompression shearing under epidote–amphibolite facies conditions.