Irrigation control for city parks, gardens and green areas

At a glance

Item	Typical answer
Problem	Green areas are watered on fixed programs set at the start of the season, so they are watered after rain, burst pipes run unnoticed, and each program change needs a visit.
What is connected	Zone valves, a water meter and a rain gauge per site, soil moisture sensors in representative zones and, in larger parks, line pressure and a cabinet door contact.
Who uses it	The parks irrigation technician, district park supervisors, the landscape manager responsible for the water budget, and contractors who maintain sites.
Typical first scope	One park with mains power and four to eight zones, plus five to ten medians or roundabouts with battery valve controllers.
Time to first screen	Typically a few days after the first gateway and meter are installed. Budget a full month of the season for a pilot that runs in notify-only mode before rules act.

The situation

A parks department, campus or landscaping contractor waters hundreds of green areas: large parks with their own pump or mains connection, sports pitches, road medians, roundabouts and planters. Most sites have a standalone irrigation controller with a seasonal program and, at best, a rain sensor that has not worked for years. Medians often have battery controllers that someone reprograms by hand at the start of each season.

The cost shows up in three ways. Water is used after rain and in the hottest hours, against municipal watering restrictions. A broken lateral or a vandalised sprinkler head runs all night until a resident reports a flooded path. Plants still die in the zones the program under-waters, because nobody knows the soil is dry until the turf browns. Water budgets are reconciled once a year from utility invoices that cannot be split by site.

This blueprint connects each site's valves, meter and rain gauge to Hermetry, keeps the existing programs where they work, and moves the decision to water into rules that check rain and soil first, with leaks and failed valves flagged within minutes.

Goals and measures

• Water use per site per day and week = increase of the meter total, in m³.
• Application depth = litres used in a zone ÷ zone area in m², which equals millimetres of water applied. Compare it with the plant type's requirement agreed with the landscape architect.
• Rain skips = scheduled runs cancelled because rain over the last 24 hours exceeded the skip limit, and the volume they would have used (run time × zone flow).
• Leak volume = metered volume while no valve is open. Night flow on an irrigation main should be zero.
• Valve faults = opens that produced no flow within the expected time.
• Budget position = season-to-date m³ ÷ season budget per site, with the expected share for the date.

Hermetry keeps minute, hourly and daily aggregates of every key; the increase aggregation turns a meter total into daily volume and treats a meter reset as a restart, not a negative volume.

Architecture

Two site types cover most portfolios, and both can run side by side in one organisation.

Parks with power

A licensed gateway in the irrigation cabinet replaces or supervises the controller. A model such as the Edge Pro LTE8421 has digital inputs, relay outputs and analog inputs, a 4G uplink and RS485 for Modbus. Relay outputs drive the zone valves through interposing relays on the 24 VAC valve supply; digital inputs read the rain gauge's tipping bucket and the meter's pulse output if the gateway model counts pulses, otherwise a meter with a Modbus output; an analog input reads a 4-20 mA line pressure transmitter. See Hermetry Edge and the licensed devices.

Where the existing controller should keep its programs, a lighter pattern works: one gateway relay opens the controller's rain sensor circuit, so Hermetry can suspend watering without touching the program, and the gateway only reads the meter and the valve outputs.

Medians and sites without power

Battery LoRaWAN devices do the work: valve controllers with latching solenoids, soil moisture sensors, and pulse readers on the meter. They join Hermetry's own LoRaWAN network server (EU868, OTAA, class A) through LoRaWAN gateways on depot roofs, park buildings or lamp posts. The codec library includes solenoid valve controllers, soil moisture sensors with temperature and conductivity, and pulse counters.

Class A devices receive a command only after their next uplink. A valve controller that reports every ten minutes may open up to ten minutes late, and a separate close command may also be late. Prefer controllers that accept a timed open (open for N minutes) so the close does not depend on a second downlink, and set the controller's own maximum run time as a safety limit.

Component	Role	Notes
Licensed gateway with relays	Valves, rain gauge, meter, pressure at powered parks	Relay commands and pulse counting depend on the gateway model and firmware; confirm them for your model.
Existing irrigation controller	Keeps its programs where they work	Suspended through its rain sensor input.
LoRaWAN valve controller	Zone valves on medians	Battery, class A; timed open preferred.
LoRaWAN soil moisture sensor	Volumetric water content in a representative zone	One per hydrozone, at root depth.
Water meter with pulse output	Site consumption, leak detection	Pulse reader over LoRaWAN, or gateway input.
Tipping-bucket rain gauge	Rain at the site or district	Gateway input or LoRaWAN pulse reader.
LoRaWAN gateway	Hears battery devices	LoRa Basics Station; gateway map and health in Hermetry.

Gateways publish over MQTT with TLS on one outbound connection and authenticate with an X.509 certificate from the platform's own authority; battery devices go through the LoRaWAN network server. Use your own SIM and operator today; eSIM management from the platform is in development.

Point list

A park with six zones, read by a gateway, plus one battery median. Inputs and register numbers are examples.

Point	Telemetry key	Unit	Source	Interval	Notes
Zone n valve state	z1_open … z6_open	0/1	Gateway relay output state	on change + 15 min	Reported by the gateway, not assumed from the command.
Any zone open	any_open	0/1	Computed in the root flow from the valve states	on change	Used by the pressure alarm.
Meter total	meter_l	L	Meter pulses on DI1, e.g. 10 L per pulse	5 min	Daily volume from the increase.
Flow rate	flow_lpm	L/min	Computed in the root flow from the meter total	5 min	Delta of litres ÷ minutes since the previous reading.
Line pressure	line_bar	bar	4-20 mA transmitter on AI1	1 min while watering, 15 min idle	Interval set with remote settings.
Rain gauge total	rain_total_mm	mm	Tipping bucket on DI2, e.g. 0.2 mm per tip	5 min
Rain over 24 hours	rain_24h_mm	mm	Computed in a flow	5 min	Used by the skip rule.
Cabinet door	door_open	0/1	Reed contact on DI3	on change	Vandalism and access.
Mains present	mains_ok	0/1	Supply monitor on DI4	on change
Program suspended	suspend_on	0/1	Relay feeding the controller's rain sensor input	on change	Hybrid sites only.
Soil moisture, zone n	soil_vwc	%	LoRaWAN sensor (codec key may differ)	30 min	One device per sensor.
Soil temperature	soil_temp_c	°C	LoRaWAN sensor	30 min	Frost check before watering.
Soil conductivity	soil_ec	µS/cm	LoRaWAN sensor	30 min	Salinity trend where reclaimed water is used.
Median valve state	valve_open	0/1	LoRaWAN valve controller	on change + 10 min
Median valve pulses	valve_pulses	count	Controller's meter input, where present	10 min
Battery	battery	%	LoRaWAN devices	with each uplink
Gateway signal	rssi_dbm	dBm	Gateway modem	15 min	If the gateway model reports it.

Asset model

Build the tree the way the parks department is organised. A common shape in Sites & Assets:

• City (Site) with the time zone; District (Area) with supervisor and rain_gauge_ref.
• Park or green area (Site) with location (needed for sunrise rules), area_m2, season_budget_m3, water_source (mains, borehole, reclaimed) and contractor.
• Irrigation zone (Area) with zone_area_m2, plant_type (turf, shrubs, trees, bedding), precip_rate_mm_h, default_run_min and moisture_target_pct.
• Devices placed where they act: the gateway and meter on the park, valves and soil sensors on their zones, the rain gauge on the park or district it represents.

Placement matters because a Rules card homed on a park can only name devices under that park. If one rain gauge serves a whole district, home the watering rules on the district, or give each park its own low-cost rain gauge. Store per-device limits as server attributes, for example max_flow_lpm on each meter, so one profile alarm rule fits every site.

Device setup

Profiles and provisioning

Create profiles per device kind: Park irrigation gateway, Valve controller (LoRaWAN), Soil sensor (LoRaWAN), Pulse reader (LoRaWAN). Licensed gateways are claimed into the organisation by scanning their code. LoRaWAN devices are added with DevEUI, JoinEUI and AppKey or imported in a batch. Check each codec's output keys on the device's recent frames; if a library codec names moisture differently from your key, save a copy and adjust it on the codec test bench.

Commands

Define the command catalog on each profile: for the gateway, for example valve.open with a zone and minutes and valve.close with a zone (method names depend on the gateway firmware); for battery controllers, the vendor's open and close frames as raw downlinks with port and hex data from the manual. Mark valve.open as basic tier so supervisors can water a bed by hand from a board control, and keep a critical, high-impact site.all_off. Every command is stored and followed from queued to successful, failed, timed out or expired. Give every queued valve command an expiry: a persistent open delivered hours late would water at noon.

Settings, intervals and firmware

On licensed gateways, remote device settings show the model's settings: input types, pulse weights, analog scaling and reporting intervals. Build a baseline per park type and apply it in waves; the job pauses if too few gateways apply it. Report pressure every minute only while watering if the gateway supports conditional intervals; otherwise every five minutes is a fair compromise. Signed gateway firmware is rolled out in waves after the season or between watering windows, with metered links waiting unless allowed.

Derived keys

Add two small flows. On the gateway profile, a delta block on meter_l with its period output gives litres per minute, saved as flow_lpm. On the rain gauge, a delta block on rain_total_mm followed by a statistics block summing a 24-hour time window gives rain_24h_mm, saved with the save telemetry block. A statistics window starts empty when the flow is changed, so avoid editing it on a rainy night.

Time and gaps

Gateways stamp readings with their synchronised clock and keep readings during an uplink outage (capacity depends on the model); LoRaWAN uplinks are stamped at reception. Late readings are stored and evaluated as a backfill without paging anyone for the past.

Dashboards

Board	Audience	Widgets and what they show
City irrigation map	Landscape manager, supervisors	Map of green areas coloured by status (watering, idle, alarm) from a status key written by a small flow; site table with today's volume, 24-hour rain, open alarms and last seen; stat for sites watering now; alarm table.
Park page	Technician, supervisor	State cards per zone valve; control buttons to open a zone for a set time behind a confirmation; line chart of flow and pressure over 48 hours with valve states; soil moisture per zone against its target; rain over 24 hours; the park's Rules card with its Manual and Auto switch.
Water budget	Landscape manager	Bar chart of daily m³ per site; progress card of season-to-date volume against budget per site; stat with trend for this week against last week; table of litres per m² per zone, downloadable to Excel.
Field technician	Technician	Device table of valves and sensors sorted by battery and last seen; table of commands that failed or timed out; LoRaWAN gateway map.

Entity parameters let one park page serve every park; a map marker click opens it with the park as parameter.

SCADA screens

Draw one irrigation schematic per park layout: supply connection, meter, backflow and isolation valves, main line, zone valves and the zones with their emitters. The agri family of the Food pack supplies Irrigation valve, Sprinkler, Drip line, Soil moisture probe, Water tank, Fertigation unit and Weather station symbols, and the city family of the Water pack supplies Water meter; pipes join them. See the symbol library.

• States. Valve symbols show open or closed from z1_open; the main line pipe colours while flow_lpm is above a few litres; a rule blinks the meter red when flow runs with every valve closed.
• Values. Each zone prints its soil moisture and today's run minutes; the meter prints flow and today's volume.
• Commands. A valve symbol can open its zone for a set time behind a confirmation that names the symbol, command and values.
• Reuse. Attach the drawing as a view of the park asset or the gateway profile; parks of the same layout get their own bindings. Match everything proposes devices, and the Problems tab lists anything unbound.

Rules and alarms

The watering rule

Each park gets a Rules card homed on the park. A typical watering rule, written in the card's When, Only if and Then blocks:

1. When: every day at a time, or one hour before sunrise using the park's coordinates, on the days the municipal order allows. A days-of-the-month condition handles odd and even day schemes.
2. Only if: the date is within the irrigation season (for example 15 April to 15 October) and soil temperature is above 3 °C.
3. Then, decide: if rain_24h_mm is at or above the skip limit (for example 5 mm), notify the supervisor that the run was skipped and stop. Otherwise, for each zone whose soil_vwc is below its target: open zone 1 for its run time; wait until flow_lpm rises above a minimum, with a five-minute timeout that raises a valve fault alarm and moves on; wait the run time; close zone 1; repeat for the next zones.

A rule holds up to 20 actions, about six zones in this pattern; parks with more zones chain a second rule with the run rule action. Skip notices with the reason are how the department learns to trust the rules; the run log also names the condition that stopped a run.

Alarm	Condition	Delay and hysteresis	Severity	Notified	Escalation
Possible leak	Rules card: flow_lpm above 3 while no zone valve is open	Stays so for 15 min	Major (raised by the rule)	District technician, push and SMS	Reminder every 30 min until acknowledged
Burst while watering	Profile rule: flow_lpm above attribute max_flow_lpm	Debounce 2 samples	Critical	Technician and supervisor, SMS	Reminder every 15 min
Valve did not open	Rules card wait-until timed out	5 min	Minor	Technician, push	None
Low line pressure while watering	Profile rule: line_bar below 1.5 and any_open = 1, a key the root flow writes from the valve states	Debounce 3 samples; hysteresis 0.3 bar	Major	Technician, push	Reminder every 30 min
Cabinet opened	Profile rule: door_open = 1	Debounce 1 sample	Warning	Supervisor, push	None
Mains failure	Profile rule: mains_ok = 0	Debounce 60 s	Major	Technician, push	Reminder every 60 min
Device silent	Inactivity rule, 3 × the reporting interval		Warning	Technician, e-mail	None
Battery low	Profile rule: battery below 20	Debounce 2 samples	Info	Technician, e-mail	None

The burst and pressure rules work on one device's values, so they live on the gateway profile. The leak rule compares the meter with the valves of several devices, so it lives in the Rules card; mark it Also runs in Manual so leak notices keep working when a park is in Manual.

Lifecycle. An alarm opens after its delay, is acknowledged by the technician who takes it, with an optional note, and resolves by itself when the condition clears. One alarm stays open per device and type. Severity rises re-notify; reminders repeat until acknowledged. Review resolved leaks nobody acknowledged: a leak that stopped on its own may be a valve that sticks.

Events and maintenance. For a concert or a re-seeding, set the park to Manual until a time; its rules stop and resume on their own, and while a device is in Manual no rule sends it a command. Mute a site's devices during repairs; alarms are still recorded.

Automation and integrations

• Rain skip across sites. One district rain gauge can serve several parks when the watering rules are homed on the district asset and name each park's valves; a local gauge per park is simpler to reason about.
• Work orders. alarm.created and alarm.cleared webhooks, HMAC-signed, open and close jobs in the maintenance system; a flow can add the park and zone names from the device details.
• Command outcomes. rpc.failed webhooks or the technician board catch valves that never confirmed.
• Water utility data. Budgets and invoices stay in the finance system; monthly volumes per site come from history tables exported to Excel. Scheduled reports are not built in today.

A licensed router's web panel opens from its device page through router remote access, with time-limited, audited sessions, which saves a drive for many connectivity problems.

Roles and access

Who	Role or group	Can
Irrigation technician	User + IoT operator group	See every site, acknowledge alarms, open and close zones from controls, switch sites to Manual.
District supervisor	User, narrowed to the district	See and run their parks, acknowledge alarms, use Manual.
Landscape manager	User + IoT viewer group	Read boards and budgets, export history.
Irrigation engineer	Admin	Profiles, rules, alarm rules, drawings, command catalog, gateway settings and firmware.
Maintenance contractor	Own organisation, or narrowed users	Only the sites in their contract.

A landscaping company serving several clients can keep each client in its own organisation, isolated by row-level security. Narrowing a supervisor to a district uses attribute-based policies; test them with the policy simulator. High-impact commands, rule changes, Manual switches and setting changes are written to the audit log.

Sizing and data

As an order of magnitude for 30 parks with gateways and 90 medians, counting one message per device per reading as a conservative estimate:

• Park gateways: one message every 5 minutes, 288 a day, plus about 100 change messages in the watering window: 30 × 390 ≈ 11,700 a day.
• Median valve controllers: 2 per median, one uplink every 10 minutes: 180 × 144 ≈ 25,900 a day.
• Soil sensors: 150 sensors every 30 minutes: 150 × 48 = 7,200 a day; pulse readers on 90 medians every 15 minutes: 8,640 a day.
• Total: roughly 53,000 messages a day, about 1.6 million a month; around 400,000 values a day.

Only telemetry and attribute messages count toward the allowance; commands do not. Raw readings are kept for at most 90 days, so compare seasons on hourly and daily aggregates: the 365-day class keeps them for a year, the 1,095-day class for three years. Battery life, not the platform, decides the reporting interval of median devices.

Rollout plan

Phase	Weeks	Work	Exit criteria
0. Survey	Before the season	Valve and zone inventory per site, meter and pulse weights, radio survey for medians, plant types and budgets; agree restrictions and skip limits.	Signed zone list and key names per site type.
1. Pilot	Season weeks 1-4	One park and five medians; gateway, devices, profiles, boards; rules in notify-only mode.	Each valve opened and confirmed by flow; skip notices match the weather; leak rule tested.
2. Rules act	Season weeks 5-8	Watering rules send commands; leak and burst alarms live; district supervisors trained on Manual.	Two weeks without a missed or unwanted run.
3. Districts	Rest of the season	Remaining sites district by district, with baselines and webhooks.	Every site reporting; weekly volume figures accepted by the landscape manager.
4. Off-season	Winter	Firmware rollouts, battery replacement, threshold review with the landscape architect.	Thresholds per plant type updated for next season.

Commissioning checklist

1. Gateway claimed, on the right profile and park; relay outputs mapped to the right zones, checked by eye at each zone.
2. Meter pulse weight checked: volume over ten minutes compared with the meter dial.
3. Rain gauge checked by pouring a known volume; rain_24h_mm rises accordingly.
4. Soil sensors installed at root depth in a representative spot, away from emitters; moisture compared with a hand probe.
5. Each zone opened from Hermetry: state confirmed, flow seen within the expected time, closed again.
6. Battery valve controller: timed open tested; command latency observed and noted; command expiry set.
7. Leak rule tested by opening a hose tap with all zones closed; burst rule tested with a known high flow.
8. Watering rule run once with Run now in notify-only mode; the run log explains each condition.
9. Uplink unplugged during a run: the controller or relay finishes safely; readings arrive afterwards.

Pitfalls

• Closing on a second downlink. A late or lost close command overwaters. Use timed opens and a controller-side maximum run time.
• Persistent commands without expiry. A command delivered hours late waters at the wrong time. Always set an expiry.
• One moisture sensor for mixed plantings. Place a sensor per hydrozone, not per park, and set targets per plant type.
• Rain gauges under trees or near walls. They under-read and cause unnecessary watering. Site them in the open.
• Coarse meter pulses. At 100 litres per pulse a small leak takes hours to show. Choose a fine pulse weight for leak detection.
• Rules acting from day one. Run a few weeks in notify-only mode so supervisors see why each run happened.
• Forgetting frost. Watering at dawn on a frosty morning ices paths. Keep a soil or air temperature condition in every rule.

What Hermetry does not replace

Hermetry decides and supervises; it does not replace the hydraulic and electrical protection on site. Backflow prevention, pressure regulation, pump protection, the controller's local maximum run time and any manual isolation stay in the field and must work when the link or the platform is down. A command from Hermetry is a request that a gateway or controller may fail to carry out, which is why every valve state is read back. Water billing, budgets and contracts stay in the finance and contract systems.