scholarly journals Assessing Hydrological Impacts of a Watershed in the Context of Climate and Land Cover Changes

2017 ◽  
Author(s):  
Dong-Sin Shih ◽  
Ray-Shyan Wu ◽  
Chung-Yuan Tsai
Keyword(s):  
Land Cover ◽  
General Circulation ◽  
Circulation Model ◽  
Water Levels ◽  
Land Cover Changes ◽  
Mountainous Area ◽  
Wet Season ◽  
Climate Conditions ◽  
Groundwater Levels ◽  
Hydrological Impacts

This paper proposes a method to utilize weather and land cover models to generate future environmental scenarios, and presents the watershed models to simulate the hydrological impact on watershed-scale hydrology. The Weather Generator model and General Circulation Model were applied to produce rainfall and local temperature under different climate conditions, and the Conservation and Land Use and its Effects model was incorporated to simulate future land cover variability. The circumstances of future climate and land cover changes were used as inputs to drive the HEC-HMS rainfall runoff model for obtaining surface runoff in a mountainous area. The WASH123D model was then utilized for the entire watershed simulation. Modeling results were then examined to discuss hydrological impacts on three different time periods: near future (2020-2039), future (2050-2069), and distant future (2080-2099). The Fengshan Creek basin in northern Taiwan was selected as study site. Simulations results indicated that the influence of climate change revealed more relevant effects when compared to local land cover changes. The ground water levels tended to diminish as the land cover area changed. In addition, both river and groundwater levels reveal that it is drier in dry season and wetter in wet season in future.

scholarly journals A Comparative Frequency Analysis of Maximum Daily Rainfall for a SE Asian Region under Current and Future Climate Conditions

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Velautham Daksiya ◽  
Pradeep Mandapaka ◽  
Edmond Y. M. Lo
Keyword(s):  
General Circulation ◽  
Daily Rainfall ◽  
Circulation Model ◽  
Dry Season ◽  
Wet Season ◽  
Climate Conditions ◽  
Rainfall Extremes ◽  
Annual Maximum Daily Rainfall ◽  
The Impact ◽  
Maximum Daily Rainfall

The impact of changing climate on the frequency of daily rainfall extremes in Jakarta, Indonesia, is analysed and quantified. The study used three different models to assess the changes in rainfall characteristics. The first method involves the use of the weather generator LARS-WG to quantify changes between historical and future daily rainfall maxima. The second approach consists of statistically downscaling general circulation model (GCM) output based on historical empirical relationships between GCM output and station rainfall. Lastly, the study employed recent statistically downscaled global gridded rainfall projections to characterize climate change impact rainfall structure. Both annual and seasonal rainfall extremes are studied. The results show significant changes in annual maximum daily rainfall, with an average increase as high as 20% in the 100-year return period daily rainfall. The uncertainty arising from the use of different GCMs was found to be much larger than the uncertainty from the emission scenarios. Furthermore, the annual and wet seasonal analyses exhibit similar behaviors with increased future rainfall, but the dry season is not consistent across the models. The GCM uncertainty is larger in the dry season compared to annual and wet season.

Wildfires in Europe: the role of land use/land cover changes

2020 ◽  
Author(s):  
Joana Parente ◽  
Marj Tonini ◽  
Zoi Stamou ◽  
Nikos Koutsias ◽  
Mário Pereira
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Methodological Approach ◽  
Environmental Drivers ◽  
Land Cover Changes ◽  
Land Use Land Cover ◽  
Climate Conditions ◽  
European Forest ◽  
Burnt Areas ◽  
Land Cover Maps

<p>Wildfire (WF) has the potential to occur in more than 30% of the worldwide land area, in many different biomes/ecosystems/land cover types, where it is controlled mainly by the environmental drivers such as vegetation structure, meteorological/climate conditions, and human activities. On the other hand, land use/land cover changes (LULCC) are one of the most important global alterations of the environment. In the last decades, Europe registered significant-high fire incidence and LULCC between all land cover classes. In the 2000 – 2018 period, according to the European Forest Fire Information System (EFFIS), Europe was affected by 18 882 WFs which burned 6 887,713 ha. According to CORINE land cover maps, the observed LULCC area in Europe for the same period was of 23,510,075 ha. Recent studies suggested that regional LULCC in the last decades promoted the occurrence of more and larger WF, in some European regions. Therefore, the main objectives of this study were to assessed the LULCC in and around burnt areas (BAs) during the 2000–2018 period. This study benefits from the use of reliable CORINE inventories and EFFIS BA product. A geospatial methodological approach was implemented to identify and quantify LULCC and to characterize the relationship between LULCC and WFs in Europe. This research provides a detailed characterization of the LULCC in and around BAs in Europe, and attempts to contribute to a better management of the landscape, urbanization and wildland-urban interface to reduce related losses in the natural and human system including losses of life, property and assets.</p>

On the Synergistic Climatic Effects of Covarying Major Mountain Range Topographies

2020 ◽  
Author(s):  
Sebastian G. Mutz ◽  
Todd A. Ehlers
Keyword(s):  
General Circulation ◽  
Atmospheric Transport ◽  
Circulation Model ◽  
Careful Consideration ◽  
Mountain Range ◽  
Earth Surface ◽  
Climatic Effects ◽  
Climate Conditions ◽  
Mountain Ranges ◽  
The Impact

<p>The interpretation of Earth surface archives often requires consideration of distant off-site events. One such event is the surface uplift of Earth’s major mountain ranges, which affects climate and the Earth’s surface globally. In this study, the individual and synergistic climatic effects of topographic changes in major mountain ranges are explored with a series of General Circulation Model (GCM) experiments and analyses of atmospheric teleconnections. The GCM experiments are forced with different topographic scenarios for Himalaya-Tibet (TBT) and the Andes (ADS), while environmental boundary conditions are kept constant. The topographic scenarios are constructed by successively lowering modern topography to 0% of its modern height in increments of 25%. This results in a total of 5 topographic scenarios for TBT (tbt100, tbt075, tbt050, tbt025, tbt000) and ADS (ads100, ads075, ads050, ads025, ads000). TBT scenarios are then nested in ADS scenarios, resulting in a total of 25 experiments with unique topographic settings. The climate for each of those 25 scenarios is simulated with the GCM ECHAM5-wiso. We then explore possible synergies and distant impacts of topographic changes by testing the hypothesis that varying ADS has no effect on simulated climate conditions in the TBT region (c_tbt) and vice versa. This can be expressed as the null hypothesis c_tbt(ads100) = c_tbt(ads075) = c_tbt(ads050) = c_tbt(ads025) = c_tbt(ads000) for each of the 5 TBT scenarios, and vice versa. We conduct Kruskal-Wallis tests for a total of 10 treatment sets to address these hypotheses. The results suggest that ADS climate is mostly independent of TBT topography changes, whereas TBT climate is sensitive to ADS topography changes when TBT topography is high, but insensitive when TBT topography is strongly reduced. Analyses of atmospheric pressure fields suggest that TBT height acts as a control on cross-equatorial atmospheric transport and modifies the impact of ADS topography on northern hemisphere climate. These results dictate a more careful consideration of global (off-site) conditions in the interpretation of Earth surface records.</p>

Optimal white spruce breeding zones for Ontario under current and future climates

2010 ◽  
Vol 40 (8) ◽  
pp. 1576-1587 ◽  
Author(s):  
Ashley M. Thomson ◽  
Kevin A. Crowe ◽  
William H. Parker
Keyword(s):  
Picea Glauca ◽  
General Circulation ◽  
Circulation Model ◽  
White Spruce ◽  
General Circulation Models ◽  
Future Climate ◽  
Decision Support Model ◽  
Climate Conditions ◽  
Seed Transfer ◽  
Significant Difference

Optimal breeding zones were developed for white spruce ( Picea glauca (Moench) Voss) in Ontario under present and future climate conditions to examine potential shifts due to climate change. These zones were developed by (i) determining a set of candidate breeding zones based on the relationship between measured performance variables and climate and (ii) employing a decision support model to select subsets of breeding zones that maximize geographic coverage subject to a constraint on the maximum number of zones. Current optimal breeding zones were based on 1961–1990 climate normals, and future breeding zones were based on three general circulation model (CGCM2, HADCM3, and CSIRO) predictions of 2041–2070 climate. Based on a maximum adaptive distance of 2.0 least significant difference values between sites within zones, 14 zones were required to cover the Ontario range of white spruce for the 1961–1990 data. Compared with breeding zones of other boreal conifers, current optimal breeding zones for white spruce were quite large, spanning up to 3° latitude and 10°–12° longitude and indicating large distances of effective seed transfer. Of the three general circulation models used to simulate future climate, HADCM3 B2 and CGCM2 B2 predicted 2041–2070 breeding zones that largely coincide with 1961–1990 zones. In contrast, CSIRO B2 indicated much narrower 2041–2070 breeding zones.

scholarly journals Recent trends and drivers of regional sources and sinks of carbon dioxide

2015 ◽  
Vol 12 (3) ◽  
pp. 653-679 ◽  
Author(s):  
S. Sitch ◽  
P. Friedlingstein ◽  
N. Gruber ◽  
S. D. Jones ◽  
G. Murray-Tortarolo ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Land Use ◽  
Land Cover ◽  
General Circulation ◽  
Significant Trend ◽  
Atmospheric Co2 ◽  
Plant Production ◽  
Land Cover Changes ◽  
Growing Season Length ◽  
Ocean Models

Abstract. The land and ocean absorb on average just over half of the anthropogenic emissions of carbon dioxide (CO2) every year. These CO2 "sinks" are modulated by climate change and variability. Here we use a suite of nine dynamic global vegetation models (DGVMs) and four ocean biogeochemical general circulation models (OBGCMs) to estimate trends driven by global and regional climate and atmospheric CO2 in land and oceanic CO2 exchanges with the atmosphere over the period 1990–2009, to attribute these trends to underlying processes in the models, and to quantify the uncertainty and level of inter-model agreement. The models were forced with reconstructed climate fields and observed global atmospheric CO2; land use and land cover changes are not included for the DGVMs. Over the period 1990–2009, the DGVMs simulate a mean global land carbon sink of −2.4 ± 0.7 Pg C yr−1 with a small significant trend of −0.06 ± 0.03 Pg C yr−2 (increasing sink). Over the more limited period 1990–2004, the ocean models simulate a mean ocean sink of −2.2 ± 0.2 Pg C yr−1 with a trend in the net C uptake that is indistinguishable from zero (−0.01 ± 0.02 Pg C yr−2). The two ocean models that extended the simulations until 2009 suggest a slightly stronger, but still small, trend of −0.02 ± 0.01 Pg C yr−2. Trends from land and ocean models compare favourably to the land greenness trends from remote sensing, atmospheric inversion results, and the residual land sink required to close the global carbon budget. Trends in the land sink are driven by increasing net primary production (NPP), whose statistically significant trend of 0.22 ± 0.08 Pg C yr−2 exceeds a significant trend in heterotrophic respiration of 0.16 ± 0.05 Pg C yr−2 – primarily as a consequence of widespread CO2 fertilisation of plant production. Most of the land-based trend in simulated net carbon uptake originates from natural ecosystems in the tropics (−0.04 ± 0.01 Pg C yr−2), with almost no trend over the northern land region, where recent warming and reduced rainfall offsets the positive impact of elevated atmospheric CO2 and changes in growing season length on carbon storage. The small uptake trend in the ocean models emerges because climate variability and change, and in particular increasing sea surface temperatures, tend to counter\\-act the trend in ocean uptake driven by the increase in atmospheric CO2. Large uncertainty remains in the magnitude and sign of modelled carbon trends in several regions, as well as regarding the influence of land use and land cover changes on regional trends.

scholarly journals Monitoring NDVI Inter-Annual Behavior in Mountain Areas of Mainland Spain (2001–2016)

2018 ◽  
Vol 10 (12) ◽  
pp. 4363 ◽  
Author(s):  
Patricia Arrogante-Funes ◽  
Carlos Novillo ◽  
Raúl Romero-Calcerrada
Keyword(s):  
Land Cover ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Agricultural Land ◽  
Land Cover Changes ◽  
Mountainous Area ◽  
Statistical Association ◽  
Mountain Areas ◽  
Mountain Ranges ◽  
Statistical Trends

Currently, there exists growing evidence that warming is amplified with elevation resulting in rapid changes in temperature, humidity and water in mountainous areas. The latter might result in considerable damage to forest and agricultural land cover, affecting all the ecosystem services and the socio-economic development that these mountain areas provide. The Mediterranean mountains, moreover, which host a high diversity of natural species, are more vulnerable to global change than other European ecosystems. The protected areas of the mountain ranges of peninsular Spain could help preserve natural resources and landscapes, as well as promote scientific research and the sustainable development of local populations. The temporal statistical trends (2001–2016) of the MODIS13Q1 Normalized Difference Vegetation Index (NDVI) interannual dynamics are analyzed to explore whether the NDVI trends are found uniformly within the mountain ranges of mainland Spain (altitude > 1000 m), as well as in the protected or non-protected mountain areas. Second, to determine if there exists a statistical association between finding an NDVI trend and the specific mountain ranges, protected or unprotected areas are studied. Third, a possible association between cover types in pure pixels using CORINE (Co-ordination of Information on the Environment) land cover cartography is studied and land cover changes between 2000 and 2006 and between 2006 and 2012 are calculated for each mountainous area. Higher areas are observed to have more positive NDVI trends than negative in mountain areas located in mainland Spain during the 2001–2016 period. The growing of vegetation, therefore, was greater than its decrease in the study area. Moreover, differences in the size of the area between growth and depletion of vegetation patterns along the different mountains are found. Notably, more negatives than expected are found, and fewer positives are found than anticipated in the mountains, such as the Cordillera Cantábrica (C.Cant.) or Montes de Murcia y Alicante (M.M.A). Quite the reverse happened in Pirineos (Pir.) and Montes de Cádiz y Málaga (M.C.M.), among others. The statistical association between the trends found and the land cover types is also observed. The differences observed can be explained since the mountain ranges in this study are defined by climate, land cover, human usage and, to a small degree, by land cover changes, but further detailed research is needed to get in-depth detailed conclusions. Conversely, it is found that, in protected mountain areas, a lower NDVI pixels trend than expected (>20%) occurs, whereas it is less than anticipated in unprotected mountain areas. This could be caused by management and the land cover type.

Evaluation of the impacts of deep open drains on groundwater levels in the wheatbelt of Western Australia

2004 ◽  
Vol 55 (11) ◽  
pp. 1159 ◽  
Author(s):  
Riasat Ali ◽  
Tom Hatton ◽  
Richard George ◽  
John Byrne ◽  
Geoff Hodgson
Keyword(s):  
Western Australia ◽  
Discharge Rate ◽  
Soil Surface ◽  
Extreme Rainfall ◽  
Water Levels ◽  
Extreme Rainfall Event ◽  
Wet Season ◽  
Initial Water ◽  
Groundwater Levels ◽  
The Impact

Abstract. Over one million hectares of the wheatbelt of Western Australia (WA) are affected by secondary salinisation and this area is expected to increase to between 3 and 5 million hectares if current trends continue. Deep open drains, as an engineering solution to dryland salinity, have been promoted over the past few decades; however, the results of initial experiments were variable and no thorough analysis has been done. This research quantifies the effects of deep open drains on shallow and deep groundwater at farm and subcatchment level. Analysis of rainfall data showed that the only dry year (below average rainfall) after the construction of drainage in the Narembeen area of WA (in 1998 and 1999) was 2002. The dry year caused some decline in groundwater levels in the undrained areas but had no significant impact in the drained areas. The study found that the effect of drains on the groundwater levels was particularly significant if the initial water levels were well above the drain bed level, permeable materials were encountered, and drain depth was adequate (2.0–3.0 m). Visual observations and evidence derived from this study area suggested that if the drain depth cut through more permeable, macropore-dominated siliceous and ferruginous hardpans, which exist 1.5–3 m from the soil surface, its efficiency exceeded that predicted by simple drainage theory based on bulk soil texture. The effect of drains often extended to distances away (>200 m) from the drain. Immediately following construction, drains had a high discharge rate until a new hydrologic equilibrium was reached. After equilibrium, flow largely comprised regional groundwater discharge and was supplemented by quick responses driven by rainfall recharge. Comparison between the hydrology of the drained and undrained areas in the Wakeman subcatchment showed that, in the valley floors of the drained areas, the water levels fluctuated mainly between 1.5 and 2.5 m of the soil surface during most of the year. In the valley floors of the undrained areas, they fluctuated between 0 and 1 m of the soil surface. The impact of an extreme rainfall event (or unusual wet season) on drain performance was predicted to vary with distance from the drain. Within 100 m from the drain, water levels declined relatively quickly, whereas it took a year before the water levels at 200–300 m away from the drain responded. The main guidelines that can be recommended based on the results from this study are the drain depth and importance of ferricrete layer. In order to be effective, a drain should be more than 2 m deep and it should cut through the ferricrete layer that exists in many landscapes in the wheatbelt.

scholarly journals Onset and End of the Rainy Season in South America in Observations and the ECHAM 4.5 Atmospheric General Circulation Model

2007 ◽  
Vol 20 (10) ◽  
pp. 2037-2050 ◽  
Author(s):  
Brant Liebmann ◽  
Suzana J. Camargo ◽  
Anji Seth ◽  
José A. Marengo ◽  
Leila M. V. Carvalho ◽  
...  
Keyword(s):  
Rainy Season ◽  
General Circulation ◽  
Rain Rate ◽  
Atmospheric General Circulation Model ◽  
Circulation Model ◽  
Season Length ◽  
Wet Season ◽  
Atmospheric General Circulation ◽  
Annual Total ◽  
Sst Anomalies

Abstract Rainfall in South America as simulated by a 24-ensemble member of the ECHAM 4.5 atmospheric general circulation model is compared and contrasted with observations (in areas in which data are available) for the period 1976–2001. Emphasis is placed on determining the onset and end of the rainy season, from which its length and rain rate are determined. It is shown that over large parts of the domain the onset and ending dates are well simulated by the model, with biases of less than 10 days. There is a tendency for model onset to occur early and ending to occur late, resulting in a simulated rainy season that is on average too long in many areas. The model wet season rain rate also tends to be larger than observed. To estimate the relative importance of errors in wet season length and rain rate in determining biases in the annual total, adjusted totals are computed by substituting both the observed climatological wet season length and rate for those of the model. Problems in the rain rate generally are more important than problems in the length. The wet season length and rain rate also contribute substantially to interannual variations in the annual total. These quantities are almost independent, and it is argued that they are each associated with different mechanisms. The observed onset dates almost always lie within the range of onset of the ensemble members, even in the areas with a large model onset bias. In some areas, though, the model does not perform well. In southern Brazil the model ensemble average onset always occurs in summer, whereas the observations show that winter is often the wettest period. Individual members, however, do occasionally show a winter rainfall peak. In southern Northeast Brazil the model has a more distinct rainy season than is observed. In the northwest Amazon the model annual cycle is shifted relative to that observed, resulting in a model bias. No interannual relationship between model and observed onset dates is expected unless onset in the model and observations has a mutual relationship with SST anomalies. In part of the near-equatorial Amazon, there does exist an interannual relationship between onset dates. Previous studies have shown that in this area there is a relationship between SST anomalies and variations in seasonal total rainfall.

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