scholarly journals The impact of forest regeneration on streamflow in 12 meso-scale humid tropical catchments

2013 ◽  
Vol 10 (3) ◽  
pp. 3045-3102 ◽  
Author(s):  
H. E. Beck ◽  
L. A. Bruijnzeel ◽  
A. I. J. M. van Dijk ◽  
T. R. McVicar ◽  
F. N. Scatena ◽  
...  
Keyword(s):  
Time Series ◽  
Land Cover ◽  
Forest Regeneration ◽  
Forest Area ◽  
Apparent Lack ◽  
Macro Scale ◽  
Annual Time Series ◽  
The Impact ◽  
Annual Time ◽  
Meso Scale

Abstract. Although regenerating forests make up an increasingly large portion of humid tropical landscapes, comparatively little is known of their water use and effects on streamflow (Q). Since the 1950s the island of Puerto Rico has experienced widespread abandonment of pastures and agricultural lands, followed by forest regeneration. This paper examines the possible impacts of forest regeneration on several Q metrics for 12 meso-scale catchments (23–346 km2; mean precipitation 1720–3422 mm yr−1) with long (33–51 yr) and simultaneous records for Q, precipitation (P), potential evapotranspiration (PET), and land cover. A simple spatially-lumped, conceptual rainfall-runoff model that uses daily P and PET time series as inputs (HBV-light) was used to simulate Q for each catchment. Annual time series of observed and simulated values of four Q metrics were calculated. A least-squares trend was fitted through annual time series of the residual difference between observed and simulated time series of each Q metric. From this the total cumulative change  was calculated, representing the change in each metric after controlling for climate variability and water storage carry-over effects between years. Negative values of  were found for most catchments and Q metrics, suggesting enhanced actual evapotranspiration overall following forest regeneration. However, correlations between changes in urban or forest area and values of  were insignificant (p ≥ 0.389) for all Q metrics. This suggests there is no convincing evidence that changes in the chosen Q metrics in these Puerto Rican catchments can be ascribed to changes in urban or forest area. The present results are in line with previous studies of meso- and macro-scale (sub-)tropical catchments, which generally found no significant change in Q that can be attributed to changes in forest cover. Possible explanations for the apparent lack of a clear signal may include: errors in the land-cover, climate, Q, and/or catchment boundary data; changes in forest area occurring mainly in the less rainy lowlands; and heterogeneity in catchment response. Different results were obtained for different catchments, and using a smaller subset of catchments could have led to very different conclusions. This highlights the importance of including multiple catchments in land-cover impact analysis at the meso scale.

scholarly journals The impact of forest regeneration on streamflow in 12 mesoscale humid tropical catchments

2013 ◽  
Vol 17 (7) ◽  
pp. 2613-2635 ◽  
Author(s):  
H. E. Beck ◽  
L. A. Bruijnzeel ◽  
A. I. J. M. van Dijk ◽  
T. R. McVicar ◽  
F. N. Scatena ◽  
...  
Keyword(s):  
Time Series ◽  
Land Cover ◽  
Forest Regeneration ◽  
Forest Cover ◽  
Impact Analysis ◽  
Forest Area ◽  
Macro Scale ◽  
Annual Time Series ◽  
The Impact ◽  
Annual Time

Abstract. Although regenerating forests make up an increasingly large portion of humid tropical landscapes, little is known of their water use and effects on streamflow (Q). Since the 1950s the island of Puerto Rico has experienced widespread abandonment of pastures and agricultural lands, followed by forest regeneration. This paper examines the possible impacts of these secondary forests on several Q characteristics for 12 mesoscale catchments (23–346 km2; mean precipitation 1720–3422 mm yr−1) with long (33–51 yr) and simultaneous records for Q, precipitation (P), potential evaporation (PET), and land cover. A simple spatially-lumped, conceptual rainfall–runoff model that uses daily P and PET time series as inputs (HBV-light) was used to simulate Q for each catchment. Annual time series of observed and simulated values of four Q characteristics were calculated. A least-squares trend was fitted through annual time series of the residual difference between observed and simulated time series of each Q characteristic. From this the total cumulative change (Â) was calculated, representing the change in each Q characteristic after controlling for climate variability and water storage carry-over effects between years. Negative values of  were found for most catchments and Q characteristics, suggesting enhanced actual evaporation overall following forest regeneration. However, correlations between changes in urban or forest area and values of  were insignificant (p ≥ 0.389) for all Q characteristics. This suggests there is no convincing evidence that changes in the chosen Q characteristics in these Puerto Rican catchments can be ascribed to changes in urban or forest area. The present results are in line with previous studies of meso- and macro-scale (sub-)tropical catchments, which generally found no significant change in Q that can be attributed to changes in forest cover. Possible explanations for the lack of a clear signal may include errors in the land cover, climate, Q, and/or catchment boundary data; changes in forest area occurring mainly in the less rainy lowlands; and heterogeneity in catchment response. Different results were obtained for different catchments, and using a smaller subset of catchments could have led to very different conclusions. This highlights the importance of including multiple catchments in land-cover impact analysis at the mesoscale.

scholarly journals Land Cover Mapping of a Tropical Region by Integrating Multi-Year Data into an Annual Time Series

2015 ◽  
Vol 7 (12) ◽  
pp. 16274-16292 ◽  
Author(s):  
Jesús Anaya ◽  
René Colditz ◽  
Germán Valencia
Keyword(s):  
Time Series ◽  
Land Cover ◽  
Tropical Region ◽  
Land Cover Mapping ◽  
Annual Time Series ◽  
Annual Time

scholarly journals Impact of Fiscal Deficit on Inflation in Sri Lanka: An Econometric Time Series Analysis

2016 ◽  
Vol 70 ◽  
pp. 8-13
Author(s):  
A.L.M. Aslam ◽  
S.M. Ahamed Lebbe
Keyword(s):  
Time Series ◽  
Sri Lanka ◽  
Price Index ◽  
Time Series Data ◽  
Consumer Price Index ◽  
Series Data ◽  
Fiscal Deficit ◽  
Annual Time Series ◽  
The Impact ◽  
Annual Time

There is a relationship between the fiscal deficit and inflation, which was confirmed empirically in several studies conducted in many countries. Sri Lanka has been encountering the problem of inflation for the recent years. But in Sri Lanka, this proposition has not yet been studied scientifically. Therefore, this study was going to fill this gap. The objective of this study was to test the impact of fiscal deficit on inflation in Sri Lanka. For this study, the annual time series data were used during the period of 1959 to 2013. The fiscal deficit, exchange rate, government expenditures and import outflow were used as independent variables while the Colombo consumer price index was considered as dependent variable. In addition, the multiple regressions model was used to test the impact of fiscal deficit on inflation. Based on the regression results, the fiscal deficit preserved the positive relationship with inflation in Sri Lanka at one percent significant level. Therefore, this study confirmed that the fiscal deficit accelerates the inflation in Sri Lanka.

scholarly journals Assessment of Annual Composite Images Obtained by Google Earth Engine for Urban Areas Mapping Using Random Forest

2021 ◽  
Vol 13 (4) ◽  
pp. 748
Author(s):  
Zhaoming Zhang ◽  
Mingyue Wei ◽  
Dongchuan Pu ◽  
Guojin He ◽  
Guizhou Wang ◽  
...  
Keyword(s):  
Time Series ◽  
Random Forest ◽  
Urban Areas ◽  
Google Earth ◽  
Landsat 8 ◽  
Annual Time Series ◽  
Google Earth Engine ◽  
Time Series Images ◽  
The Impact ◽  
Annual Time

Urban areas represent the primary source region of greenhouse gas emissions. Mapping urban areas is essential for understanding land cover change, carbon cycles, and climate change (urban areas also refer to impervious surfaces, i.e., artificial cover and structures). Remote sensing has greatly advanced urban areas mapping over the last several decades. At present, we have entered the era of big data. Long time series of satellite data such as Landsat and high-performance computing platforms such as Google Earth Engine (GEE) offer new opportunities to map urban areas. The objective of this research was to determine how annual time series images from Landsat 8 Operational Land Imager (OLI) can effectively be composed to map urban areas in three cities in China in support of GEE. Three reducer functions, ee.Reducer.min(), ee.Reducer.median(), and ee.Reducer.max() provided by GEE, were selected to construct four schemes to synthesize the annual intensive time series Landsat 8 OLI data for three cities in China. Then, urban areas were mapped based on the random forest algorithm and the accuracy was evaluated in detail. The results show that (1) the quality of annual composite images was improved significantly, particularly in reducing the impact of cloud and cloud shadows, and (2) the annual composite images obtained by the combination of multiple reducer functions had better performance than that obtained by a single reducer function. Further, the overall accuracy of urban areas mapping with the combination of multiple reducer functions exceeded 90% in all three cities in China. In summary, a suitable combination of reducer functions for synthesizing annual time series images can enhance data quality and ensure differences between characteristics and higher precision for urban areas mapping.

scholarly journals Mapping canopy damage from understory fires in Amazon forests using annual time series of Landsat and MODIS data

2011 ◽  
Vol 115 (7) ◽  
pp. 1706-1720 ◽  
Author(s):  
Douglas C. Morton ◽  
Ruth S. DeFries ◽  
Jyoteshwar Nagol ◽  
Carlos M. Souza ◽  
Eric S. Kasischke ◽  
...  
Keyword(s):  
Time Series ◽  
Modis Data ◽  
Annual Time Series ◽  
Annual Time ◽  
Canopy Damage

Using annual time-series of Landsat images to assess the effects of forest restitution in post-socialist Romania

2012 ◽  
Vol 118 ◽  
pp. 199-214 ◽  
Author(s):  
Patrick Griffiths ◽  
Tobias Kuemmerle ◽  
Robert E. Kennedy ◽  
Ioan V. Abrudan ◽  
Jan Knorn ◽  
...  
Keyword(s):  
Time Series ◽  
Landsat Images ◽  
Annual Time Series ◽  
Annual Time

Income and Price Elasticities in India's Trade

1994 ◽  
Vol 19 (2) ◽  
pp. 13-20
Author(s):  
G S Gupta ◽  
H Keshava
Keyword(s):  
Time Series ◽  
Time Series Data ◽  
Series Data ◽  
Individual Country ◽  
Price Elasticities ◽  
The World ◽  
Annual Time Series ◽  
Income And Price Elasticities ◽  
Annual Time

This article by G S Gupta and H Keshava estimates the export and import functions for India both at the aggregate (rest of the world) as well as the important individual country levels using annual time series data for the period 1960-61 through 1990-91.

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