Our ability to numerically model natural systems has progressed enormously over the last 10–20 years. During the last decade computational power has increased to the stage where we can now have a super-computer on our desk, and the detail and fine scale processes that can be included in models are fantastic. The computational tools available for analysis and display have opened doors beyond the dreams of our forebears. However, as modelling power has increased there has been a concurrent reduction in “data power”, particularly in the collection of hydrological data. While we undoubtedly have access to large datasets of extraordinary technological finesse such as the remotely sensed data from satellites, our collection of more basic and traditional datasets suffers. We can read car number plates from outer space, but we still, in the main, measure rainfall by putting a bucket out in a paddock. This paper discusses the growth in sophistication of hydrological modelling through the last hundred years. The concept of validation or verification of models is questioned, and the role of data in modelling discussed. It is argued that modelling in the absence of adequate data is not science, unless it is to develop hypotheses that are to be tested by observation. Several modelling case studies with and without adequate testing data are discussed. It is also argued that improvement in the management of our environment and water resources will not come with improved models in the absence of improved data collection because we cannot manage what we do not measure.

Hydrological models are so good, do we still need data?

The role of agroforestry and perennial pasture in mitigating water logging and secondary salinity: summary

. The establishment of a catchment monitoring network is a process, from the inception of the idea to its implementation, the latter being the construction of relevant gauging structures and installation of the various instruments. It is useful that the local communities and other stakeholders are involved and participate in such a process, as was highlighted during the establishment of the hydrological monitoring network in the Potshini catchment in Bergville District in the KwaZulu-Natal Province, South Africa. The paper highlights the participatory establishment of a hydrological monitoring network in a small rural inhabited catchment, in line with the overall objective of the Smallholder System Innovations (SSI) research programme, to monitor hydrological processes at both field and catchment scale for water resources management research purposes. The engagement and participation of the Potshini community precipitated a learning opportunity for both the researchers and the local community on (i) the understanding of hydrological processes inherent in the catchment (ii) appreciating the inherent dynamics in establishing a catchment monitoring network in the midst of a community (iii) paradigm shift on how to engage different stakeholders at different levels of participation. The participatory engagement in the monitoring process led to appreciation and uptake of some of the research results by the Potshini community and ensured continued support from all stakeholders. This paper is of the view that the participation of the local community and other stakeholders in catchment monitoring and instilling a sense of ownership and management of natural resources to the local communities needs to be encouraged at all times. Success stories in water resources management by local communities can be realized if such a process is integrated with other development plans in the catchment at all forums, with due recognition of the social dynamics of the communities living in the catchment.

/pdf/establishment-of-a-catchment-monitoring-network-through-a-3z7eihgpyu.pdf

Establishment of a catchment monitoring network through a participatory approach in a rural community in South Africa

Soil water relations, crop production and root pruning of a belt of trees

Rising watertables and dryland salinity in southern Australia are due to excess groundwater recharge after the replacement of native vegetation by annual crops and pastures. The inclusion of perennial plants into agricultural systems has been proposed as a possible method of recharge reduction, through the creation of a buffer (extra water storage capacity generated by the perennial in comparison with an annual crop or pasture). However, the role of perennial phases under conditions of highly episodic leakage is not well understood. In this paper, a simple Leakage/Buffer Model (LeBuM) was developed to determine the effect of perennial phases on long-term average annual leakage, incorporating episodic events. Mechanistic modelling studies on contrasting soil types were used to demonstrate that leakage for any given May–December period was directly related to soil water storage at 1 May. From this finding, it follows that leakage from a phase rotation can be calculated if the size of the buffer, and the leakage quantity in the absence of a buffer, are known for each stage of the rotation. LeBuM uses a long-term sequence of leakage values in the absence of a buffer as input, and the maximum buffer size, its rate of development, and the length of perennial and annual phases are specified as parameters. LeBuM was applied to leakage data modelled for 5 contrasting soil types over 100 years at 24 sites in the Western Australian wheatbelt. Phase rotations on duplex, waterlogging duplex, or loamy sand soils reduced leakage by >90% for regions with <380 mm annual rainfall, but were less effective in wetter regions and on deep sands or acid loamy sands. Nevertheless, phase rotations if adopted widely could delay the onset of salinity by as much as several decades.

Predicting the impact of perennial phases on average leakage from farming systems in south-western Australia

Measuring and monitoring the effects of agroforestry and drainage in the ‘Ucarro’ sub-catchment

A bio-physical modelling study is presented which simulates the drainage under an annual clover and a perennial lucerne pasture. The simulations are compared with measurements taken at a trial near Katanning, Western Australia, subject to a Mediterranean climate. The results show the water balance of the site to be dominated by the vertical dimension, with no apparent lateral flow in the B soil horizon. Drainage under lucerne was found to be less than that under the clover during the growing season of the annual pasture. However, our results suggest the dominant drainage control may be site and soil characteristics rather than pasture type. We found that using measured values of hydraulic conductivity led to much higher drainage than could be supported by observations of perched watertables within the A and B horizons. The observations suggest that the subsoils change their structure when they moisten in winter and become much less conductive. In order to model the site, a soil profile had to be invoked which reflected field water table hydrograph observations rather than soil water characteristics determined in the laboratory or from field profile texture observations.

Modelling Drainage and Transient Waterlogging in an Agricultural Catchment

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

B.H Ward

Author Tools

Chat about Author

Papers

Measuring and monitoring the effects of agroforestry and drainage in the ‘Ucarro’ sub-catchment

Modelling Drainage and Transient Waterlogging in an Agricultural Catchment