scholarly journals Mapping of water-related ecosystem services in the uMngeni catchment using a daily time-step hydrological model for prioritisation of ecological infrastructure investment – Part 1: Context and modelling approach

Water SA ◽  
2018 ◽  
Vol 44 (4 October) ◽  
Author(s):  
CJ Hughes ◽  
G De Winnaar ◽  
RE Schulze ◽  
M Mander ◽  
GPW Jewitt
Keyword(s):  
Ecosystem Services ◽  
Hydrological Model ◽  
Severe Drought ◽  
Water Shortages ◽  
Time Step ◽  
Ecological Infrastructure ◽  
High Assurance ◽  
Daily Time Step ◽  
Daily Time

South Africa is a semi-arid country which frequently faces water shortages, and experienced a severe drought in the 2016 and 2017 rainfall seasons. Government is under pressure to continue to deliver clean water to the growing population at a high assurance of supply. Studies now show that the delivery of water may be sustained not only through built infrastructure such as dams and pipelines, but also through investment in ecological infrastructure (EI). A daily time-step hydrological model was used to map areas which should be prioritised for protection or rehabilitation to sustain the delivery of water-related ecosystem services within the uMngeni catchment. We focused on three water-related ecosystem services, i.e.: water supply, sustained baseflow, erosion control/avoidance of excessive sediment losses. The two key types of degradation were modelled, namely, overgrazing and the invasion of upland areas by Black Wattle (Acacia mearnsii). This, Part 1 of a paper in 2 parts, provides a discussion on the role of EI in delivering water-related ecosystem services, describes the motivation for the study, and the methods used in modelling and mapping the catchment. The results of this modelling exercise are presented in Part 2, which also explores and illustrates the potential hydrological benefits of rehabilitation and protection of EI in the uMngeni Catchment.

scholarly journals Mapping of water-related ecosystem services in the uMngeni catchment using a daily time-step hydrological model for prioritisation of ecological infrastructure investment – Part 2: Outputs

Water SA ◽  
2018 ◽  
Vol 44 (4 October) ◽  
Author(s):  
CJ Hughes ◽  
G De Winnaar ◽  
RE Schulze ◽  
M Mander ◽  
GPW Jewitt
Keyword(s):  
Ecosystem Services ◽  
Water Yield ◽  
Severe Drought ◽  
Water Shortages ◽  
Time Step ◽  
Ecological Infrastructure ◽  
Catchment Areas ◽  
High Assurance ◽  
Daily Time Step ◽  
Water Volumes

South Africa is a semi-arid country which frequently faces water shortages, and experienced a severe drought in the 2016 and 2017 rainfall seasons. Government is under pressure to continue to deliver clean water to the growing population at a high assurance of supply. Studies now show that the delivery of water may be sustained not only through built infrastructure such as dams and pipelines, but also through investment in ecological infrastructure (EI). Part 1 of this paper in 2 parts concentrated on the role of EI in delivering water-related ecosystem services, as well as the motivation for this study, and the methods used in modelling and mapping the catchment. Part 2 explores and illustrates the current level of delivery of water-related ecosystem services in different parts of the catchment, with potential hydrological benefits of rehabilitation and protection of EI in the uMngeni catchment. The Mpendle, Lions River, Karkloof, Inanda and Durban sub-catchments are important areas for the generation of streamflows which accumulate downstream (i.e. water yield in the catchment) when annual totals are considered. Modelled annual sediment yield (in tonnes) from naturally vegetated areas is most severe in the lower catchment areas with steeper slopes such as Inanda, and in the high-altitude areas which have both steeper slopes and higher rainfall. The central and eastern parts of the uMngeni catchment were found to contribute the greatest yield of sediment from degraded areas with low protective vegetation cover. This combined modelling and mapping exercise highlighted areas of priority ecosystem service delivery, such as higher altitude grassland areas, which could be recommended for formal conservation, or protection under private partnerships. Generally, these areas confirm the intuitive sense of catchment stakeholders, but provide a robust and more defendable analysis through which water volumes are quantifiable, and potential investment into catchment interventions are justified.

Alternative climate data sources for distributed hydrological modelling on a daily time step

2010 ◽  
Vol 25 (10) ◽  
pp. 1542-1557 ◽  
Author(s):  
Ashraf El-Sadek ◽  
Max Bleiweiss ◽  
Manoj Shukla ◽  
Steve Guldan ◽  
Alexander Fernald
Keyword(s):  
Hydrological Modelling ◽  
Data Sources ◽  
Climate Data ◽  
Time Step ◽  
Daily Time Step ◽  
Distributed Hydrological Modelling ◽  
Daily Time

Daily Time-Step Refinement of Optimized Flood Control Rule Curves for a Global Warming Scenario

2011 ◽  
Vol 137 (4) ◽  
pp. 309-317 ◽  
Author(s):  
Se-Yeun Lee ◽  
Carolyn J. Fitzgerald ◽  
Alan F. Hamlet ◽  
Stephen J. Burges
Keyword(s):  
Global Warming ◽  
Flood Control ◽  
Time Step ◽  
Control Rule ◽  
Warming Scenario ◽  
Rule Curves ◽  
Daily Time Step ◽  
Global Warming Scenario ◽  
Daily Time

A model of expansion and senescence of individual leaves of field-grown maize (Zea mays L.)

1994 ◽  
Vol 74 (1) ◽  
pp. 37-42 ◽  
Author(s):  
D. W. Stewart ◽  
L M. Dwyer
Keyword(s):  
Leaf Area ◽  
Zea Mays L ◽  
Growth Models ◽  
Time Step ◽  
Leaf Area Expansion ◽  
Daily Time Step ◽  
Area Expansion ◽  
Area Development ◽  
Leaf Area Development ◽  
Daily Time

Estimation of leaf area is a major component of plant growth models. In this study, a model was developed to calculate field-grown maize leaf area expansion and senescence on an individual leaf basis. The model began with an equation, based on cumulative growing degree-days from emergence, to initiate leaf area development. The model required daily values of maximum and minimum air temperature, solar radiation and precipitation, had essentially a daily time step with day and night modes, and could be run on commonly accessible computers (micros to mainframes). The objective of the development of the model was to assist plant breeders in optimizing leaf number and shape for adaptation to specific environments. Key words: Leaf area and number, temperature, phenological development

Analysis of the Dynamics of Adaptation to Transgenic Corn and Crop Rotation by Western Corn Rootworm (Coleoptera: Chrysomelidae) Using a Daily Time-Step Model

2005 ◽  
Vol 98 (2) ◽  
pp. 534-551 ◽  
Author(s):  
D. W. Crowder ◽  
D. W. Onstad ◽  
M. E. Gray ◽  
C.M.F. Pierce ◽  
A. G. Hager ◽  
...  
Keyword(s):  
Crop Rotation ◽  
Western Corn Rootworm ◽  
Corn Rootworm ◽  
Transgenic Corn ◽  
Time Step ◽  
Step Model ◽  
Daily Time Step ◽  
Daily Time

scholarly journals Evaluation of a MODIS-Based Potential Evapotranspiration Product at the Point Scale

2008 ◽  
Vol 9 (3) ◽  
pp. 444-460 ◽  
Author(s):  
Jongyoun Kim ◽  
Terri S. Hogue
Keyword(s):  
Potential Evapotranspiration ◽  
Simple Algorithm ◽  
Sensor Data ◽  
Net Radiation ◽  
Point Scale ◽  
Time Step ◽  
Satellite Platform ◽  
Daily Time Step ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Daily Time

Abstract This paper outlines the development of a continuous, daily time series of potential evapotranspiration (PET) using Moderate Resolution Imaging Spectroradiometer (MODIS) sensor data from the Terra satellite platform. The approach is based on the Priestley–Taylor equation, incorporating a daily net radiation model during cloudless days. A simple algorithm using “theoretical clear-sky” net radiation (incorporating daily cloud fraction and cloud optical thickness) and PET is then used to estimate net radiation and PET under cloudy conditions. The method requires minimal ground-based observations for initial calibration of regional radiation algorithm coefficients. Point-scale comparisons are undertaken at four flux-tower sites in North America covering a range of hydroclimatic conditions and biomes. Preliminary results at the daily time step for a 4-yr period (2001–04) show good correlation (R2 = 0.89) and low bias (0.34 mm day−1) for three of the more humid sites. Results are further improved when aggregated to the monthly time scale (R2 = 0.95, bias = 0.31 mm day−1). Performance at the semiarid site is less satisfactory (R2 = 0.95, bias = 2.05 mm day−1 at the daily time step). In general, the MODIS-based daily PET estimates derived in this study are promising and show the potential for use in theoretical and operational water resource studies in both gauged and ungauged basins.

scholarly journals Runoff modelling in glacierized Central Asian catchments for present-day and future climate

2006 ◽  
Vol 37 (2) ◽  
pp. 93-105 ◽  
Author(s):  
W. Hagg ◽  
L.N. Braun ◽  
M. Weber ◽  
M. Becht
Keyword(s):  
Tien Shan ◽  
Water Shortages ◽  
Time Step ◽  
Climate Conditions ◽  
Central Asian ◽  
Complex Picture ◽  
Daily Time Step ◽  
The Alps ◽  
High Degree ◽  
Tien Shan Mountains

A conceptual precipitation–runoff model was applied in five glacierized catchments in Central Asia. The model, which was first developed and applied in the Alps, works on a daily time step and yields good results in the more continental climate of the Tien Shan mountains for present-day climate conditions. Runoff scenarios for different climates (doubling of CO2) and glacierization conditions predict an increased flood risk as a first stage and a more complex picture after a complete glacier loss: a higher discharge during spring due to an earlier and more intense snowmelt is followed by a water deficiency in hot and dry summer periods. This unfavourable seasonal redistribution of the water supply has dramatic consequences for the Central Asian lowlands, which depend to a high degree on the glacier melt water for irrigation and already nowadays suffer from water shortages.

Simulation of the water and isotopic balance of a closed tropical lake at a daily time step (Lake Ihotry, South-West of Madagascar)

2006 ◽  
Vol 88 (1-3) ◽  
pp. 153-156 ◽  
Author(s):  
Christine Vallet-Coulomb ◽  
Françoise Gasse ◽  
Laurent Robison ◽  
Luc Ferry
Keyword(s):  
Tropical Lake ◽  
Time Step ◽  
South West ◽  
Daily Time Step ◽  
Daily Time
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