Irrigation | Timon Weitkamp | No Worries, Just Maps

Mapping smallholder irrigation in Mozambique

Tue, 10 Nov 2026 00:00:00 +0000

Many smallholder farmers in Mozambique irrigate. They dig their own canals, use buckets or small pumps, and grow vegetables close to a river. Most of this never ends up in official statistics, so it is also missing when governments plan water use. Mapping it from space sounds easy and isn’t. The fields are small, mixed with rainfed crops, and look different from one valley to the next.

For the FASIMO programme (farmer-led and smallholder irrigation in Gaza and Manica, 12 schemes and about 1,000 farmers) I developed the remote sensing method and wrote the reports on irrigated area. They became a practical basis for government water resource planning in Mozambique.

My PhD went deeper into the method. Algorithm, training data, composite length and model transfer between regions each change the result. Two analysts can make two quite different maps of the same area. So I also proposed a reporting framework, so readers can see which choices were made.

In Messica we tested what Sentinel-1 radar adds to Sentinel-2 in dense time series. I used Sentinel-1 from Digital Earth Africa in the workflow and learned where SAR helps, and where its temporal and spatial scale limits it for this kind of small-field mapping.

The newest step is geospatial foundation model embeddings. At the WaterNet symposium in 2026 I presented a comparison of Sentinel-2 with AlphaEarth and TESSERA embeddings, and how far models built on them transfer between regions and years.

Satellite embeddings for smallholder irrigation mapping: how far do the models transfer?

Wed, 28 Oct 2026 00:00:00 +0000

In my PhD, models for mapping smallholder irrigation transferred badly from one region in Mozambique to another. Geospatial foundation models promise features that work everywhere, so I tested whether that holds for irrigation.

I compared plain Sentinel-2 with embeddings from two foundation models, AlphaEarth and TESSERA. I trained classifiers in one study area, applied them in another, and also transferred them between years (2021 and 2022), using the field data from my PhD study areas.

More about mapping smallholder irrigation

Identifying smallholder irrigation through remote sensing: challenges and way forward

Wed, 29 Oct 2025 00:00:00 +0000

A talk on the challenges of mapping smallholder irrigation with remote sensing, based on my PhD and the work in Mozambique since.

More about mapping smallholder irrigation

PhD defence: Uncharted territory

Fri, 02 Feb 2024 00:00:00 +0000

On 2 February 2024 I defended my PhD thesis in Wageningen.

About the PhD · Read the thesis