Do you recall specific memorable personal or work experience that has led you to this point in your career – tell us where it all began?
Well, I started having a passion for Earth observation when I was studying for my bachelor of science degree back in 2003 at the University of Zimbabwe. My then lecturer at the university (now a Minister of Higher and Tertiary Education in Zimbabwe), who had just came from abroad was full of passion, zeal and he would ooze out GIS and Earth Observation. I then said wow, I would like to become like him one day. The way he would articulate the applications of spatial data in water and environmental science motivated me to go on and apply for a scholarship to study for a master’s degree in Geoinformation Science with specific focus in water resources management. I was admitted at the International Institute of Geoinformation Science and Earth Observation (ITC) of the University of Twente through the NUFFIC scholarship. The experience though the 1.5- year study period made me realise that we can solve a lot of water, sanitation, climate and environmental problems that happen on earth through the application of geospatial data. In my current PhD work, I process satellite rainfall images, extract sensitive information for hydrological modelling. The research output is expected to improve water resources management in the vast Zambezi basin which cuts across Southern Africa.
What excites you about your current research work on spatial hydrology and water resource management?
The Zambezi basin in Southern Africa, currently faces acute shortages of water resources in terms of quantity and quality. Spatial hydrology allows professionals in the field to quantify the critical water resources in space and time. Earth Observation data analysis allows one to zoom into specific regions of the country facing water management challenges thus contributing to finding specific solutions to address those challenges. Back in my country Zimbabwe, I recently led a team in a national project of mapping wetlands of Zimbabwe. The fact that the spatial databases and maps that came from this project led to a masterplan that guides developmental projects in water and environmental conservation makes me proud of my work.
How will this research contribute towards enhancing resilience to water risks – how will this work benefit the society?
My recent research work has also focused on mapping and modelling floods and landslides in eastern Zimbabwe and western Mozambique, through the use of Earth observation data and hydraulic models. By providing maps of flood hazard and landslide risk areas, it assists, communities to be aware of areas that are prone to these hydrological and meteorological disasters as well as assist researchers and civil protection leaders in preparing for the next events. Without maps it is very impossible to pinpoint safe and unsafe areas. Thus, maps help to stir imaginations and are an important tool in reducing disaster risks. During floods and landslides, satellite communication services such as mobile short messaging services (SMS) and web based information depend on or are fed by space data, thus going a long way in saving lives as well as in the mitigation of catastrophic outcomes of any event. In other words, communities and institutions resilience levels are increased through space-based research and implementation of disaster preparedness, mitigation, during and post disasters measures as well as early warning systems.
Describe the potential of geospatial technologies and how these techniques can be leveraged to support IWRM and hydrology respectively.
Information required for IWRM is often spatial and satellite-derived information. It helps overcome limited data availability and has the advantage of being spatially distributed with global coverage. In many parts of Sub-Saharan Africa, in-situ measurements of key hydrometeorological variables such as rainfall, evaporation and streamflow are associated with data gaps and are at times discontinuous. This is because of lack of ground stations and well-designed gauge networks. Geospatial technologies provide information on the above variables to represent real-world spatiotemporal distributions, to observe rates, and to assess occurrence, in regions where installation of gauge networks is limited. In short, as the adage goes: ‘what we can measure accurately, we can manage accurately’, it also relates to the application of geospatial technologies which can be leveraged to accurately manage water resources.
One of the most important aspects of hydrological modelling in water management is uncertainties. Therefore, it is very important to reduce uncertainty in model development. How has the integration of Earth Observation data improved hydrological models' developments?
Hydrological models are essential tools for generating information on water resources as well as water-related disasters (e.g., flood peak, inundation depths, and inundation extents). Advances in hydrological modelling are driven by availability of spatially distributed ground and satellite data. Therefore, once preprocessed and adequately bias corrected, Earth observation data inputs can serve hydrological and water resource modelling. In most cases, models are calibrated with sparse gauge network and incomplete records. As such the output cannot be trusted. The parameterisation of hydrological models using Earth observation data sets such as satellite-based rainfall and digital elevation models (DEM) allows for the reduction of uncertainties in model development. Of course, this is a subject of continuous research and discussion.
What are the advantages and drawbacks of hydrological modelling that fully relies on satellite data, i.e., calibrating and running the model using satellite precipitation and evaporation as forcing, and satellite-based estimates of river discharge as benchmark data for the calibration?
Satellite based products, however, only are representations of reality with specific spatial (i.e., the pixel footprint) and temporal resolutions (revisit time) and thus representations by the various satellite product developers are dissimilar. The use of Earth observation-based inputs such as satellite rainfall estimates in hydrological modelling therefore requires understanding of how effects of satellite rainfall errors propagate to effect streamflow simulation mismatch. Trying to understand as to what extent the errors in modelling forcing propagate to water balance estimation mismatch has been part of my research efforts in the past decade. Therefore, I advocate that bias correction of satellite based meteorological forcing is critical as it can yield to substantial improvement in capturing both, streamflow pattern and magnitude for effective water resources management and disaster management.
What potential do you see in the use of UAVs in combination with space-based technology and data? Do you have any examples of cases / projects where you were involved in the use of Unmanned Aerial Vehicles (UAVS) for water resources assessments and/or hydrological hazard mapping? What were the main challenges and how can these be overcome?
Unmanned Aerial Vehicles or Drones are very handy especially in areas that we would have identified as areas of focus using satellite images. In other words, with UAV, we zoom in to those specific areas, which can either be landslides prone areas, areas of flood damage or areas where we want to monitor water use or illegal water connections. High resolution images and can be taken and used for various projects. When Cyclone Idai ravaged Chimanimani District of Zimbabwe, as University of Zimbabwe, we flew drones on affected areas in order to monitor at close range as well as to manage the extent of the disaster. Another example is when we participated in land suitability for irrigation in Midlands Province of Zimbabwe. With the UAV images we managed to acquire images of soil type, soil moisture indices as well as topographical variables. Such type of data went on to inform agricultural and water managers on the amounts of water resources needed for the irrigation project.
Can you elaborate on the potential of remote sensing for monitoring dams?
Most water resources infrastructure such as dams in Southern Africa face threats of siltation due to unmonitored land-use activities in the catchment upstream of the infrastructure. Furthermore, climate change is projected to reduce dam inflows because of reduced rainfall activity. As such, remote sensing technologies can be employed to map land-use and land-cover changes with satellites such as Landsat which its use spans from the early 1970s as well as Sentinel which introduces improved spatial resolution. With these images, water quality parameters linked to upstream land-uses can also be automatically retrieved from specific sites in the dams. Nowadays water levels in the dams and bathymetric information such as depths and shapes of underwater terrain can be mapped from space as compared to the traditional approaches of using water surveying equipment. Our recent study at the University of Zimbabwe demonstrated the utility satellite data where we linked hydropower production at Lake Kariba to dam water levels and rainfall activities upstream of the dam.
Can you expand on recent innovation in space technology for hydrology and water resource management?
Several multi-satellite products such as for landcover assessment, elevation extraction, weather data estimation, have been developed with the objective to improve hydrological applications and water resources management. For the purpose of improving precipitation estimation techniques in space and time, approaches depending on the visible infrared (VIS/IR) and the passive microwave have also been developed to retrieve satellite precipitation. Satellite retrieval of soil moisture, evapotranspiration, and other water cycle components also exist. Furthermore, Artificial intelligence (AI)- based approaches using various deep learning and machine learning-based algorithms to understand data in any of the spatiotemporal forms have been developed. The biggest challenge has been figuring out how to improve both, the spatial and temporal resolution of satellites whilst making the products accessible and affordable for developing nations. With regards to precipitation information, several multi-satellite precipitation products such as The Climate Prediction Center morphing method (CMORPH), The Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN) and Tropical Rainfall Measuring Mission (TRMM) have been developed with the objective to improve satellite rainfall estimates at sub-daily time step. This is a big improvement since rainfall rates and intensities can now be estimated in space.
From your experience, do you think youth in the Southern African Development Community (SADC) region is aware of and understanding the role and potential of space technology in addressing most environmental /climate-related challenges?
Yes, but this has been limited to the young people who are university students or graduates. Applications of space technologies have been taught in specific disciplines within higher and tertiary institutions. These disciplines are limited to geography, civil and water engineering, surveying and environmental sciences. The primary and secondary school learners are still to be exposed to this powerful technology which we believe can transform societies. There are also young people who are past the secondary school stage, the youth in this age group is involved in developmental or income-based projects which interact with the physical environment such as mineral exploration, agriculture etc. Space technologies such as With regards to precision farming and precision mining, space-based technologies and data can help to identify exactly where to exploit resources for the developmental projects mentioned above and to refine and concentrate efforts to those localities thus saving time, saving costs and improving efficiency.
What can be done to raise awareness of the potential of such technologies to solve environmental challenges at national / local levels?
Space technology should be introduced at elementary (primary and secondary) levels so that learners are location intelligent, that is, have the ability at an early education level to analyse and find spatial patterns in data; to provide powerful insights into understanding our world and communicating our needs. This also means that policy makers need to be conscientized of the vast potential of space technology for national development.
In your current post as a lecturer in hydrology and meteorology what are your challenges and lessons learned? And, what can we learn from the young generation?
It has been challenging to teach students at postgraduate level the latest space technologies because the students are at the tail end of their formal learning and academic curve. Ideally, the skills could have been implemented at undergraduate and elementary levels. Then again, the shortage of resources to purchase high resolution images as well as the necessary equipment such as UAVs, Lidar data and other equipment such as Global positioning System (GPS) to validate the satellite-based estimates.
On the other side, it has been a joy to be a pioneer of this fairly new discipline in Zimbabwe, more so in the water and engineering sector. Because of their rich mathematical and physics background, engineering students embrace space technology quite better and this has been a joy in my journey as a lecturer in space technology applications for water resources management.
What advice would you have for a young professional looking to launch a career in your field? What were the challenges and how did you address them? What are the opportunities?
There has been rapid growth in the use of digital spatial and temporal data for hydrology, water resources management, sanitation management and suitability assessment through the use of Geographic Information Systems (GIS). Young professionals in developing countries such as Zimbabwe should understand that the use of space technology for improved service delivery has not been fully explored and therefore there is a gap to be filled. In other words, a lot of job openings and opportunities are going to exist in the near future in local municipalities, rural district councils, local water boards to just name a few. The common challenges that are faced by young professionals is that it is rare to find fully fledged GIS/Earth Observation Offices well designed for you in these institutions. One has to be aggressive and introduce the skills, and desirable outputs. When I started at the University of Zimbabwe’s Civil Engineering Department, there were no courses in GIS and earth observation in water engineering and management. By researching in areas that shows the potential of these tools and techniques in the water management, I was able to present a strong case that these courses are needed from undergraduate to postgraduate studies. Leaders of institutions cannot be expected to embrace technologies that they have not seen the impact. My advice to the young professionals is to be aggressive a little bit and to show that what is spatial (space technologies and GIS skills) is indeed special because these technologies and skills can improve the way water resources are managed especially in developing nations. Things that are accurately mapped are accurately managed, and this is what young experts working with spatial water resources should show when they join any institution.
Can you recommend a few very good online training resources to get started using space-based data to address water issues?
I can recommend young professionals to follow short courses by the University of Twente’s Institute of Geoinformation Science and Earth Observation and specifically by the Water Resources Department. I have personally been impacted by both physical and online courses. I have organised and facilitated GIS and remote sensing (RS) courses for the University of Zimbabwe’s Construction and Civil Engineering Department as well as the Institute of Water and Sanitation Development located in Zimbabwe. These courses target and look to develop and improve GIS and RS skillsets of people in the following career fields: water and sanitation engineering, town/physical planning, project managers, technicians, plumbers, consulting engineers, environmental impact assessment (EIA) professionals, public health practitioners, researchers, etc.
