End Zero Flow Ruaha predicted January 19, 2023

^{The newest post and image entries are on top of the page. Scroll from the bottom upwards to follow the flow status timeline} ^{of the Ruaha River per location}

Flow Ruaha River at Mtera confirmed

Sentinel-2 Image (width 2.8km) of the return of flow at Mtera (VDAS Alert Two) on January 23, 2023. The River at the bottom of the image is probably the Little Ruaha and their confluence. This will need to be confirmed on a clear day (Click to enlarge)

Considering the advance of the surface flow in the Ruaha River on January 18, 2023 (image below) the zero flow period for the river between the source and the Mtera Reservoir will end on January 19, 2023.

The surface water flow in the Ruaha River (blue) has reached within 8km of the Mtera VDAS (Alert Two) on the right side of the image in the morning of January 18, 2023. Click on image to enlarge.

Advancing surface flow Ruaha River not yet at Mtera

With the departure of the clouds (see image below of December 29, 2022) the advance of the surface flow from the Ruaha River is located some 47.5km upstream of the Mtera Alert Two virtual remote sensing station.

The 20mm per pixel resolution image shows the water channel has reached a section of 47.5km upstream of the Mtera VDAS (Alert Two) on January 8, 2023. The zero flow period in sections of the Ruaha River still continues.

On December 29, 2022 the surface flow in the Ruaha has not yet reached Mtera (20km upstream of reservoir).

Dry Riverbed Ruaha River on December 29, 2022 some 20 km upstream of the Mtera Reservoir. The width of the image is 2.3km. (Click to enlarge)

Due to the cloud cover on December 26, 2022 the advance of the surface flow front in the Ruaha River cannot be traced between Msembe Bridge and Mtera. From the Landsat 8 image it can be concluded that the zero flow period at Mtera has not yet ended.

The VDAS location for the zero flow monitor still has no traces of the returning flow in the Ruaha on December 26, 2022.

Recession Surface Flow Ruaha some 200km from Mtera

On December 1, 2022 the surface flow in the Ruaha River as it flows out of the park has dried even upstream of the Msembe Bridge. But with the ongoing rains of November and early December 2022, the flow is expected to reach the Ruaha again at the Park HQ (Msembe Bridge) soon.

Panchromatic image from Landsat 8 December 1, 2022 shows isolated pools in the Ruaha River upstream and downstream of the Msembe Bridge (Park HQ) indicating the retreat of the surface flow from the Mtera Reservoir to the section between the Park HQ and the Ihefu Swamp (Map). (Click on Image to enlarge)

Flow Out Of Park and Mtera 2022

For conclusions on the impact of the changed flow regime of the Ruaha River on the aquatic life and other dependent species like wildlife and riverine vegetation and ultimately the impact on the communities who make use of the River, the flow monitor will assist in description and classification of the river flow, pool occurrence and duration and periods of zero flow. The handbook : “Intermittent Rivers & Ephemeral Streams: What water managers need to know” financed by the European Union considers some basic monitoring requirements for managing ecosystems impacted by a changing river regime.

It is remotely observed that with zero flow occurrence at the Park Headquarter at Msembe Bridge a (subsoil) flow is still continuing downstream of the bedrock at the bridge. This continued trickle will continue to refresh the pools in the riverbed used by the Hippopotamus population during the low flow period and reduce the risk of the deadly anthrax ²⁵. For short zero flow periods the risk of anthrax break out is expected to be smaller than during long periods of zero flow in the park.

The Flow Monitor can assist in preventing or reducing the period of zero flow.

Near Infrared Image with 20m pixels shows the continued flow with near or complete zero flow at the Msembe Bridge (Park HQ) at the bottom left) Click to enlarge. The detail (5m/px) of the riverbed flow is visualised below. The status of the pools at the Mwagusi Sand River confluence with the Ruaha is monitored to keep track of the refuge for the hippopotamus and other aquatic species.

Near infrared (5m/px) detail of the Ruaha river with zero flow some 3 km upstream at the Msembe Bridge (Park HQ) (click to enlarge)

Land and Water Composite manupulated to 5m/px but based on 20m SWIR 1 band and therefor less sharp. For scale see upper left corner.

In 2016 Keenan Stears and his team studied²⁶. the behavior and ecology of hippopotamus in the Ruaha Park in response to the reduced (zero) flow in the river. The GPS tracked animals were monitored. (see image below). The occurrence of anthrax possibly linked to the reduced flows further expanded their research. It will be interesting to investigate the length of the zero flow period or even its absence on the impact on aquatic life including the hippopotamus population.

Movement (GPS track) of one of the hippos along the Ruaha River at the Park Headquarter. The red dots represent Anthrax infected Pools in the Ruaha River bed. (Image Source https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.3540)

Pool Status Monitor Zero Flow Period 2022

Three days into the zero flow period of the Park HQ at Msembe the pool at the confluence with the Mwagusi Sand River and Ruaha River covered an area of 2223sqm one both earlier on July 3, 2022 the size of the pool was twice as much,

The 3m/px PlanetScope Image of December 2, 2018 which was 25 days into the zero flow period at the Msembe Bridge (Park HQ) the pool was reduced to 820 sqm.

The high resolution image of January 25, 2017 which was already 96 days into an intermittent period of flow and zero flow at the Msembe Bridge (Park HQ) shows a large pool of approximately 3200 sqm surface area. The confluence of the Mwagusi Sand River and the Ruaha River is 20.25km as the bird flies.

The recession of the flow out of the park from Mtera towards Msembe at 40km downstream of Park HQ.

In 2021 the recession of the reducing outflow in the Park, after drying at Mtera, showed drying of the Msembe to Mtera section of the Ruaha River. In three month time the front of the drying river retreated some 100km (as the bird flies) between Mtera Reservoir and the Msembe Bridge (Park HQ). Zero Flow at Mtera (Alert One) was observed on August 31, 2021 and the image of the dry Ruaha Riverbed with unconnected pools over the 100km stretch taken on December 29, 2021. The flow returned on January 3, 2022.

Dry Riverbed Ruaha at Msembe Bridge after 3 months zero flow period on December 12, 2021 the dark blue stretches are pools.(click to enlarge)

On August 11, 2022, the day the Ruaha dried 2km upstream of the Msembe Bridge (Park HQ) the recession of the surface flow downstream of the Msembe Bridge has reached 40km from the bridge. In a period of almost one month since the Ruaha dried at Mtera.

Recession Front drying Ruaha River in Ruaha River Section 40km from Msembe Bridge on August 11, 2022

Alert Two at Mtera July 17, 2022

The first observation of zero flow at the virtual drainage assessment station (VDAS) used for detecting the flow status of the Ruaha River at Mtera is on July 17 2022.

The flow pattern from flow in the Ruaha to zero flow at the VDAS has changed in 2022. Visit the 2021-2022 pattern here which pattern has been steady for a number of years.

Below you can see the drying of the Ruaha close to the Mtera Reservoir and upstream of the confluence with the Little Ruaha River in a sequence of three images with newest image on top. (click images to enlarge)

Zero Flow in the Ruaha River some 10km upstream of Mtera Reservoir and 6.5km to the confluence with the Little Ruaha on July 17, 2022

The Flow in the Ruaha at Alert One June 12, 2022

The NBR composite image gives an impression of the natural and irrigated crop “losses” (Dark green, green and dark blue) at the time Alert Phase One starts. There is adequate water in the system to boost drainage to the Ruaha National Park to delay the zero flow at the Park HQ.

Dark green, green and dark blue reflect the areas with high atmospheric loss of water vapour due to Irrigation, Spill and Riverine vegetation. Especially wastage from drainage canals, filling of unregulated irrigation canals and resulting spill in swamps and other depressions. The image is on June 10, 2022 two days before Alert One.(click to enlarge)

First Alert at Mtera June 12, 2022

The First Alert for the Rufiji Basin Water Office to start following the water use in Kapunga and Ifushiro is announced on June 12, 2022.